From b1009e803268de50c8e6057c7317667779a1d373 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Thu, 9 Aug 2018 23:45:52 +0100
Subject: [PATCH 1/6] Remove e.suppressReactErrorLogging check before last
 resort throw

It's unnecessary here. It was here because this method called console.error().
But we now rethrow with a clean stack, and that's worth doing regardless of whether the logging is silenced.
---
 .../src/ReactFiberCommitWork.js                | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.js b/packages/react-reconciler/src/ReactFiberCommitWork.js
index 42aa93a356857..f126796b0bf67 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.js
@@ -112,17 +112,13 @@ export function logError(boundary: Fiber, errorInfo: CapturedValue<mixed>) {
   try {
     logCapturedError(capturedError);
   } catch (e) {
-    // Prevent cycle if logCapturedError() throws.
-    // A cycle may still occur if logCapturedError renders a component that throws.
-    const suppressLogging = e && e.suppressReactErrorLogging;
-    if (!suppressLogging) {
-      // Rethrow it from a clean stack because this function is assumed to never throw.
-      // We can't safely call console.error() here because it could *also* throw if overridden.
-      // https://github.com/facebook/react/issues/13188
-      setTimeout(() => {
-        throw e;
-      });
-    }
+    // This method must not throw, or React internal state will get messed up.
+    // If console.error is overridden, or logCapturedError() shows a dialog that throws,
+    // we want to report this error outside of the normal stack as a last resort.
+    // https://github.com/facebook/react/issues/13188
+    setTimeout(() => {
+      throw e;
+    });
   }
 }
 

From dd9f09de8b661e9c712092565ef167e2101497fd Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Mon, 13 Aug 2018 19:51:21 +0100
Subject: [PATCH 2/6] Don't print error addendum if 'error' event got
 preventDefault()

---
 .../src/ReactFiberErrorLogger.js              | 18 +++++++++++
 .../src/ReactFiberScheduler.js                | 12 +++++++-
 packages/shared/ReactErrorUtils.js            | 30 +++++++++++++++++--
 .../ReactErrorUtils-test.internal.js          |  2 +-
 packages/shared/invokeGuardedCallback.js      | 14 +++++++--
 5 files changed, 70 insertions(+), 6 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberErrorLogger.js b/packages/react-reconciler/src/ReactFiberErrorLogger.js
index a5a4f756abc81..aad7042804191 100644
--- a/packages/react-reconciler/src/ReactFiberErrorLogger.js
+++ b/packages/react-reconciler/src/ReactFiberErrorLogger.js
@@ -9,6 +9,8 @@
 
 import type {CapturedError} from './ReactCapturedValue';
 
+import ReactErrorUtils from 'shared/ReactErrorUtils';
+
 import {showErrorDialog} from './ReactFiberErrorDialog';
 
 export function logCapturedError(capturedError: CapturedError): void {
@@ -35,6 +37,22 @@ export function logCapturedError(capturedError: CapturedError): void {
       willRetry,
     } = capturedError;
 
+    // Browsers support silencing uncaught errors by calling
+    // `preventDefault()` in window `error` handler.
+    if ((ReactErrorUtils: any).isErrorSuppressedInDEV(error)) {
+      if (errorBoundaryFound && willRetry) {
+        // The error is recoverable and was silenced.
+        // Ignore it and print the stack addendum.
+        // This is handy for testing error boundaries without noise.
+        return;
+      }
+      // The error is fatal. Since the silencing might have
+      // been accidental, we'll surface it anyway.
+      // However, the browser would have silenced the original error
+      // so we'll print it first, and then print the stack addendum.
+      console.error(error);
+    }
+
     const componentNameMessage = componentName
       ? `The above error occurred in the <${componentName}> component:`
       : 'The above error occurred in one of your React components:';
diff --git a/packages/react-reconciler/src/ReactFiberScheduler.js b/packages/react-reconciler/src/ReactFiberScheduler.js
index bca85e65a6f21..b77562dd7fa3c 100644
--- a/packages/react-reconciler/src/ReactFiberScheduler.js
+++ b/packages/react-reconciler/src/ReactFiberScheduler.js
@@ -301,7 +301,17 @@ if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
     // Replay the begin phase.
     isReplayingFailedUnitOfWork = true;
     originalReplayError = thrownValue;
-    invokeGuardedCallback(null, workLoop, null, isYieldy);
+    const didSuppressError = invokeGuardedCallback(
+      null,
+      workLoop,
+      null,
+      isYieldy,
+    );
+    if (didSuppressError) {
+      // If logging of the replayed error was suppressed,
+      // we'll also remember that for the original error.
+      (ReactErrorUtils: any).markErrorAsSuppressedInDEV(thrownValue);
+    }
     isReplayingFailedUnitOfWork = false;
     originalReplayError = null;
     if (hasCaughtError()) {
diff --git a/packages/shared/ReactErrorUtils.js b/packages/shared/ReactErrorUtils.js
index ef3cb31a78370..40230188a73c9 100644
--- a/packages/shared/ReactErrorUtils.js
+++ b/packages/shared/ReactErrorUtils.js
@@ -42,8 +42,8 @@ const ReactErrorUtils = {
     d: D,
     e: E,
     f: F,
-  ): void {
-    invokeGuardedCallback.apply(ReactErrorUtils, arguments);
+  ): boolean | void {
+    return invokeGuardedCallback.apply(ReactErrorUtils, arguments);
   },
 
   /**
@@ -105,6 +105,32 @@ const ReactErrorUtils = {
   },
 };
 
+if (__DEV__) {
+  (ReactErrorUtils: any)._suppressedErrorsInDEV =
+    typeof WeakSet === 'function' ? new WeakSet() : null;
+
+  (ReactErrorUtils: any).markErrorAsSuppressedInDEV = function(error: any) {
+    const suppressedErrors = (ReactErrorUtils: any)._suppressedErrorsInDEV;
+    if (
+      suppressedErrors != null &&
+      error != null &&
+      typeof error === 'object'
+    ) {
+      suppressedErrors.add(error);
+    }
+  };
+
+  (ReactErrorUtils: any).isErrorSuppressedInDEV = function(
+    error: any,
+  ): boolean {
+    const suppressedErrors = (ReactErrorUtils: any)._suppressedErrorsInDEV;
+    if (suppressedErrors != null) {
+      return suppressedErrors.has(error);
+    }
+    return false;
+  };
+}
+
 let rethrowCaughtError = function() {
   if (ReactErrorUtils._hasRethrowError) {
     const error = ReactErrorUtils._rethrowError;
diff --git a/packages/shared/__tests__/ReactErrorUtils-test.internal.js b/packages/shared/__tests__/ReactErrorUtils-test.internal.js
index b0a6b58137584..421da6bcf7eaf 100644
--- a/packages/shared/__tests__/ReactErrorUtils-test.internal.js
+++ b/packages/shared/__tests__/ReactErrorUtils-test.internal.js
@@ -66,7 +66,7 @@ describe('ReactErrorUtils', () => {
       'arg1',
       'arg2',
     );
-    expect(returnValue).toBe(undefined);
+    expect(returnValue).toBe(true);
     expect(ReactErrorUtils.hasCaughtError()).toBe(true);
     expect(ReactErrorUtils.clearCaughtError()).toBe(error);
   });
diff --git a/packages/shared/invokeGuardedCallback.js b/packages/shared/invokeGuardedCallback.js
index fa6ee451c9193..d1dea469d7a2d 100644
--- a/packages/shared/invokeGuardedCallback.js
+++ b/packages/shared/invokeGuardedCallback.js
@@ -124,15 +124,23 @@ if (__DEV__) {
       let error;
       // Use this to track whether the error event is ever called.
       let didSetError = false;
+      let didSuppressError = false;
       let isCrossOriginError = false;
 
-      function onError(event) {
+      const onError = event => {
         error = event.error;
         didSetError = true;
         if (error === null && event.colno === 0 && event.lineno === 0) {
           isCrossOriginError = true;
         }
-      }
+        if (event.defaultPrevented) {
+          // Some other error handler has prevented default.
+          // Browsers silence the error report if this happens.
+          // We'll remember this to later decide whether to log it or not.
+          this.markErrorAsSuppressedInDEV(error);
+          didSuppressError = true;
+        }
+      };
 
       // Create a fake event type.
       const evtType = `react-${name ? name : 'invokeguardedcallback'}`;
@@ -175,6 +183,8 @@ if (__DEV__) {
 
       // Remove our event listeners
       window.removeEventListener('error', onError);
+
+      return didSuppressError;
     };
 
     invokeGuardedCallback = invokeGuardedCallbackDev;

From 977ae186978f29b047c636e83e4e738d41db4401 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Mon, 13 Aug 2018 19:51:29 +0100
Subject: [PATCH 3/6] Add fixtures

---
 .../fixtures/error-handling/index.js          | 164 +++++++++++++++++-
 fixtures/dom/src/style.css                    |   2 +-
 2 files changed, 163 insertions(+), 3 deletions(-)

diff --git a/fixtures/dom/src/components/fixtures/error-handling/index.js b/fixtures/dom/src/components/fixtures/error-handling/index.js
index b25a56fbf78b4..e278dbfcffdfd 100644
--- a/fixtures/dom/src/components/fixtures/error-handling/index.js
+++ b/fixtures/dom/src/components/fixtures/error-handling/index.js
@@ -7,9 +7,21 @@ const ReactDOM = window.ReactDOM;
 function BadRender(props) {
   props.doThrow();
 }
+
+class BadDidMount extends React.Component {
+  componentDidMount() {
+    this.props.doThrow();
+  }
+
+  render() {
+    return null;
+  }
+}
+
 class ErrorBoundary extends React.Component {
   static defaultProps = {
     buttonText: 'Trigger error',
+    badChildType: BadRender,
   };
   state = {
     shouldThrow: false,
@@ -33,7 +45,8 @@ class ErrorBoundary extends React.Component {
       }
     }
     if (this.state.shouldThrow) {
-      return <BadRender doThrow={this.props.doThrow} />;
+      const BadChild = this.props.badChildType;
+      return <BadChild doThrow={this.props.doThrow} />;
     }
     return <button onClick={this.triggerError}>{this.props.buttonText}</button>;
   }
@@ -84,6 +97,112 @@ class TriggerErrorAndCatch extends React.Component {
   }
 }
 
+function silenceWindowError(event) {
+  event.preventDefault();
+}
+
+class SilenceErrors extends React.Component {
+  state = {
+    silenceErrors: false,
+  };
+  componentDidMount() {
+    if (this.state.silenceErrors) {
+      window.addEventListener('error', silenceWindowError);
+    }
+  }
+  componentDidUpdate(prevProps, prevState) {
+    if (!prevState.silenceErrors && this.state.silenceErrors) {
+      window.addEventListener('error', silenceWindowError);
+    } else if (prevState.silenceErrors && !this.state.silenceErrors) {
+      window.removeEventListener('error', silenceWindowError);
+    }
+  }
+  componentWillUnmount() {
+    if (this.state.silenceErrors) {
+      window.removeEventListener('error', silenceWindowError);
+    }
+  }
+  render() {
+    return (
+      <div>
+        <label>
+          <input
+            type="checkbox"
+            value={this.state.silenceErrors}
+            onChange={() =>
+              this.setState(state => ({
+                silenceErrors: !state.silenceErrors,
+              }))
+            }
+          />
+          Silence errors
+        </label>
+        {this.state.silenceErrors && (
+          <div>
+            {this.props.children}
+            <br />
+            <hr />
+            <b style={{color: 'red'}}>
+              Don't forget to uncheck "Silence errors" when you're done with
+              this test!
+            </b>
+          </div>
+        )}
+      </div>
+    );
+  }
+}
+
+class SilenceRecoverableError extends React.Component {
+  render() {
+    return (
+      <SilenceErrors>
+        <ErrorBoundary
+          badChildType={BadRender}
+          buttonText={'Throw (render phase)'}
+          doThrow={() => {
+            throw new Error('Silenced error (render phase)');
+          }}
+        />
+        <ErrorBoundary
+          badChildType={BadDidMount}
+          buttonText={'Throw (commit phase)'}
+          doThrow={() => {
+            throw new Error('Silenced error (commit phase)');
+          }}
+        />
+      </SilenceErrors>
+    );
+  }
+}
+
+class TrySilenceFatalError extends React.Component {
+  container = document.createElement('div');
+
+  triggerErrorAndCatch = () => {
+    try {
+      ReactDOM.flushSync(() => {
+        ReactDOM.render(
+          <BadRender
+            doThrow={() => {
+              throw new Error('Caught error');
+            }}
+          />,
+          this.container
+        );
+      });
+    } catch (e) {}
+  };
+
+  render() {
+    return (
+      <SilenceErrors>
+        <button onClick={this.triggerErrorAndCatch}>Throw fatal error</button>
+      </SilenceErrors>
+    );
+  }
+}
+
 export default class ErrorHandlingTestCases extends React.Component {
   render() {
     return (
@@ -103,6 +222,12 @@ export default class ErrorHandlingTestCases extends React.Component {
             the BadRender component. After resuming, the "Trigger error" button
             should be replaced with "Captured an error: Oops!" Clicking reset
             should reset the test case.
+            <br />
+            <br />
+            In the console, you should see <b>two</b> messages: the actual error
+            ("Oops") printed natively by the browser with its JavaScript stack,
+            and our addendum ("The above error occurred in BadRender component")
+            with a React component stack.
           </TestCase.ExpectedResult>
           <Example
             doThrow={() => {
@@ -155,10 +280,45 @@ export default class ErrorHandlingTestCases extends React.Component {
           </TestCase.Steps>
           <TestCase.ExpectedResult>
             Open the console. "Uncaught Error: Caught error" should have been
-            logged by the browser.
+            logged by the browser. You should also see our addendum ("The above
+            error...").
           </TestCase.ExpectedResult>
           <TriggerErrorAndCatch />
         </TestCase>
+        <TestCase
+          title="Recoverable errors can be silenced with preventDefault (development mode only)"
+          description="">
+          <TestCase.Steps>
+            <li>Check the "Silence errors" checkbox below</li>
+            <li>Click the "Throw (render phase)" button</li>
+            <li>Click the "Throw (commit phase)" button</li>
+            <li>Uncheck the "Silence errors" checkbox</li>
+          </TestCase.Steps>
+          <TestCase.ExpectedResult>
+            Open the console. You shouldn't see <b>any</b> messages in the
+            console: neither the browser error, nor our "The above error"
+            addendum, from either of the buttons. The buttons themselves should
+            get replaced by two labels: "Captured an error: Silenced error
+            (render phase)" and "Captured an error: Silenced error (commit
+            phase)".
+          </TestCase.ExpectedResult>
+          <SilenceRecoverableError />
+        </TestCase>
+        <TestCase
+          title="Fatal errors cannot be silenced with preventDefault (development mode only)"
+          description="">
+          <TestCase.Steps>
+            <li>Check the "Silence errors" checkbox below</li>
+            <li>Click the "Throw fatal error" button</li>
+            <li>Uncheck the "Silence errors" checkbox</li>
+          </TestCase.Steps>
+          <TestCase.ExpectedResult>
+            Open the console. "Uncaught Error: Caught error" should have been
+            logged by React. You should also see our addendum ("The above
+            error...").
+          </TestCase.ExpectedResult>
+          <TrySilenceFatalError />
+        </TestCase>
       </FixtureSet>
     );
   }
diff --git a/fixtures/dom/src/style.css b/fixtures/dom/src/style.css
index c316bb3f37eb1..a8e1391e1d8e7 100644
--- a/fixtures/dom/src/style.css
+++ b/fixtures/dom/src/style.css
@@ -158,7 +158,7 @@ li {
 }
 
 .test-case__body {
-  padding: 0 15px;
+  padding: 10px;
 }
 
 .test-case__desc {

From c4339328782ce3c903dabb961029712fae0d51fd Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Mon, 13 Aug 2018 21:06:14 +0100
Subject: [PATCH 4/6] Use an expando property instead of a WeakSet

---
 .../fixtures/error-handling/index.js          |  5 ++--
 .../src/ReactFiberErrorLogger.js              |  5 ++--
 .../src/ReactFiberScheduler.js                | 26 ++++++++--------
 packages/shared/ReactErrorUtils.js            | 30 ++-----------------
 .../ReactErrorUtils-test.internal.js          |  2 +-
 packages/shared/invokeGuardedCallback.js      | 16 +++++-----
 6 files changed, 30 insertions(+), 54 deletions(-)

diff --git a/fixtures/dom/src/components/fixtures/error-handling/index.js b/fixtures/dom/src/components/fixtures/error-handling/index.js
index e278dbfcffdfd..8dcb8e1dc5e0a 100644
--- a/fixtures/dom/src/components/fixtures/error-handling/index.js
+++ b/fixtures/dom/src/components/fixtures/error-handling/index.js
@@ -313,9 +313,8 @@ export default class ErrorHandlingTestCases extends React.Component {
             <li>Uncheck the "Silence errors" checkbox</li>
           </TestCase.Steps>
           <TestCase.ExpectedResult>
-            Open the console. "Uncaught Error: Caught error" should have been
-            logged by React. You should also see our addendum ("The above
-            error...").
+            Open the console. "Error: Caught error" should have been logged by
+            React. You should also see our addendum ("The above error...").
           </TestCase.ExpectedResult>
           <TrySilenceFatalError />
         </TestCase>
diff --git a/packages/react-reconciler/src/ReactFiberErrorLogger.js b/packages/react-reconciler/src/ReactFiberErrorLogger.js
index aad7042804191..291dce9d3b017 100644
--- a/packages/react-reconciler/src/ReactFiberErrorLogger.js
+++ b/packages/react-reconciler/src/ReactFiberErrorLogger.js
@@ -9,8 +9,6 @@
 
 import type {CapturedError} from './ReactCapturedValue';
 
-import ReactErrorUtils from 'shared/ReactErrorUtils';
-
 import {showErrorDialog} from './ReactFiberErrorDialog';
 
 export function logCapturedError(capturedError: CapturedError): void {
@@ -39,7 +37,8 @@ export function logCapturedError(capturedError: CapturedError): void {
 
     // Browsers support silencing uncaught errors by calling
     // `preventDefault()` in window `error` handler.
-    if ((ReactErrorUtils: any).isErrorSuppressedInDEV(error)) {
+    // We record this information as an expando on the error.
+    if (error != null && error._suppressLogging) {
       if (errorBoundaryFound && willRetry) {
         // The error is recoverable and was silenced.
         // Ignore it and print the stack addendum.
diff --git a/packages/react-reconciler/src/ReactFiberScheduler.js b/packages/react-reconciler/src/ReactFiberScheduler.js
index b77562dd7fa3c..f3e81f37cd6f8 100644
--- a/packages/react-reconciler/src/ReactFiberScheduler.js
+++ b/packages/react-reconciler/src/ReactFiberScheduler.js
@@ -301,21 +301,23 @@ if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
     // Replay the begin phase.
     isReplayingFailedUnitOfWork = true;
     originalReplayError = thrownValue;
-    const didSuppressError = invokeGuardedCallback(
-      null,
-      workLoop,
-      null,
-      isYieldy,
-    );
-    if (didSuppressError) {
-      // If logging of the replayed error was suppressed,
-      // we'll also remember that for the original error.
-      (ReactErrorUtils: any).markErrorAsSuppressedInDEV(thrownValue);
-    }
+    invokeGuardedCallback(null, workLoop, null, isYieldy);
     isReplayingFailedUnitOfWork = false;
     originalReplayError = null;
     if (hasCaughtError()) {
-      clearCaughtError();
+      const replayError = clearCaughtError();
+      if (
+        replayError != null &&
+        thrownValue != null &&
+        replayError._suppressLogging
+      ) {
+        // Also suppress logging for the original error.
+        try {
+          (thrownValue: any)._suppressLogging = true;
+        } catch (inner) {
+          // Ignore.
+        }
+      }
     } else {
       // If the begin phase did not fail the second time, set this pointer
       // back to the original value.
diff --git a/packages/shared/ReactErrorUtils.js b/packages/shared/ReactErrorUtils.js
index 40230188a73c9..ef3cb31a78370 100644
--- a/packages/shared/ReactErrorUtils.js
+++ b/packages/shared/ReactErrorUtils.js
@@ -42,8 +42,8 @@ const ReactErrorUtils = {
     d: D,
     e: E,
     f: F,
-  ): boolean | void {
-    return invokeGuardedCallback.apply(ReactErrorUtils, arguments);
+  ): void {
+    invokeGuardedCallback.apply(ReactErrorUtils, arguments);
   },
 
   /**
@@ -105,32 +105,6 @@ const ReactErrorUtils = {
   },
 };
 
-if (__DEV__) {
-  (ReactErrorUtils: any)._suppressedErrorsInDEV =
-    typeof WeakSet === 'function' ? new WeakSet() : null;
-
-  (ReactErrorUtils: any).markErrorAsSuppressedInDEV = function(error: any) {
-    const suppressedErrors = (ReactErrorUtils: any)._suppressedErrorsInDEV;
-    if (
-      suppressedErrors != null &&
-      error != null &&
-      typeof error === 'object'
-    ) {
-      suppressedErrors.add(error);
-    }
-  };
-
-  (ReactErrorUtils: any).isErrorSuppressedInDEV = function(
-    error: any,
-  ): boolean {
-    const suppressedErrors = (ReactErrorUtils: any)._suppressedErrorsInDEV;
-    if (suppressedErrors != null) {
-      return suppressedErrors.has(error);
-    }
-    return false;
-  };
-}
-
 let rethrowCaughtError = function() {
   if (ReactErrorUtils._hasRethrowError) {
     const error = ReactErrorUtils._rethrowError;
diff --git a/packages/shared/__tests__/ReactErrorUtils-test.internal.js b/packages/shared/__tests__/ReactErrorUtils-test.internal.js
index 421da6bcf7eaf..b0a6b58137584 100644
--- a/packages/shared/__tests__/ReactErrorUtils-test.internal.js
+++ b/packages/shared/__tests__/ReactErrorUtils-test.internal.js
@@ -66,7 +66,7 @@ describe('ReactErrorUtils', () => {
       'arg1',
       'arg2',
     );
-    expect(returnValue).toBe(true);
+    expect(returnValue).toBe(undefined);
     expect(ReactErrorUtils.hasCaughtError()).toBe(true);
     expect(ReactErrorUtils.clearCaughtError()).toBe(error);
   });
diff --git a/packages/shared/invokeGuardedCallback.js b/packages/shared/invokeGuardedCallback.js
index d1dea469d7a2d..c0cce27cc4f1d 100644
--- a/packages/shared/invokeGuardedCallback.js
+++ b/packages/shared/invokeGuardedCallback.js
@@ -124,10 +124,9 @@ if (__DEV__) {
       let error;
       // Use this to track whether the error event is ever called.
       let didSetError = false;
-      let didSuppressError = false;
       let isCrossOriginError = false;
 
-      const onError = event => {
+      function onError(event) {
         error = event.error;
         didSetError = true;
         if (error === null && event.colno === 0 && event.lineno === 0) {
@@ -137,10 +136,15 @@ if (__DEV__) {
           // Some other error handler has prevented default.
           // Browsers silence the error report if this happens.
           // We'll remember this to later decide whether to log it or not.
-          this.markErrorAsSuppressedInDEV(error);
-          didSuppressError = true;
+          if (error != null && typeof error === 'object') {
+            try {
+              error._suppressLogging = true;
+            } catch (inner) {
+              // Ignore.
+            }
+          }
         }
-      };
+      }
 
       // Create a fake event type.
       const evtType = `react-${name ? name : 'invokeguardedcallback'}`;
@@ -183,8 +187,6 @@ if (__DEV__) {
 
       // Remove our event listeners
       window.removeEventListener('error', onError);
-
-      return didSuppressError;
     };
 
     invokeGuardedCallback = invokeGuardedCallbackDev;

From da9d6f6f64b89baeaf2d318bc1270c7a0a00f279 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Mon, 13 Aug 2018 21:21:06 +0100
Subject: [PATCH 5/6] Make it a bit less fragile

---
 .../react-reconciler/src/ReactFiberScheduler.js    | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiberScheduler.js b/packages/react-reconciler/src/ReactFiberScheduler.js
index f3e81f37cd6f8..1231e7073f21d 100644
--- a/packages/react-reconciler/src/ReactFiberScheduler.js
+++ b/packages/react-reconciler/src/ReactFiberScheduler.js
@@ -306,14 +306,14 @@ if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
     originalReplayError = null;
     if (hasCaughtError()) {
       const replayError = clearCaughtError();
-      if (
-        replayError != null &&
-        thrownValue != null &&
-        replayError._suppressLogging
-      ) {
-        // Also suppress logging for the original error.
+      if (replayError != null && thrownValue != null) {
         try {
-          (thrownValue: any)._suppressLogging = true;
+          // Reading the expando property is intentionally
+          // inside `try` because it might be a getter or Proxy.
+          if (replayError._suppressLogging) {
+            // Also suppress logging for the original error.
+            (thrownValue: any)._suppressLogging = true;
+          }
         } catch (inner) {
           // Ignore.
         }

From 2b225247a15f2f5ad3358b2f7d8201747c423430 Mon Sep 17 00:00:00 2001
From: Dan Abramov <dan.abramov@gmail.com>
Date: Mon, 13 Aug 2018 21:31:49 +0100
Subject: [PATCH 6/6] Clarify comments

---
 packages/react-reconciler/src/ReactFiberErrorLogger.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/react-reconciler/src/ReactFiberErrorLogger.js b/packages/react-reconciler/src/ReactFiberErrorLogger.js
index 291dce9d3b017..81b1c7366d2ed 100644
--- a/packages/react-reconciler/src/ReactFiberErrorLogger.js
+++ b/packages/react-reconciler/src/ReactFiberErrorLogger.js
@@ -41,7 +41,7 @@ export function logCapturedError(capturedError: CapturedError): void {
     if (error != null && error._suppressLogging) {
       if (errorBoundaryFound && willRetry) {
         // The error is recoverable and was silenced.
-        // Ignore it and print the stack addendum.
+        // Ignore it and don't print the stack addendum.
         // This is handy for testing error boundaries without noise.
         return;
       }
@@ -50,6 +50,8 @@ export function logCapturedError(capturedError: CapturedError): void {
       // However, the browser would have silenced the original error
       // so we'll print it first, and then print the stack addendum.
       console.error(error);
+      // For a more detailed description of this block, see:
+      // https://github.com/facebook/react/pull/13384
     }
 
     const componentNameMessage = componentName