Fall back to untranslated string rather than showing missing translation error

src/languageHandler.tsx

@@ -88,8 +88,25 @@ export function _td(s: string): string { // eslint-disable-line @typescript-esli
  * */
 const translateWithFallback = (text: string, options?: object): { translated?: string, isFallback?: boolean } => {
     const translated = counterpart.translate(text, { ...options, fallbackLocale: counterpart.getLocale() });
-    if (!translated || /^missing translation:/.test(translated)) {
+    if (!translated || translated.startsWith("missing translation:")) {
         const fallbackTranslated = counterpart.translate(text, { ...options, locale: FALLBACK_LOCALE });
+        if ((!fallbackTranslated || fallbackTranslated.startsWith("missing translation:"))
+            && process.env.NODE_ENV !== "development") {
+            // Even the translation via FALLBACK_LOCALE failed; this can happen if
+            //
+            // 1. The string isn't in the translations dictionary, usually because you're in develop
+            // and haven't run yarn i18n
+            // 2. Loading the translation resources over the network failed, which can happen due to
+            // to network or if the client tried to load a translation that's been removed from the
+            // server.
+            //
+            // At this point, its the lesser evil to show the untranslated text, which
+            // will be in English, so the user can still make out *something*, rather than an opaque
+            // "missing translation" error.
+            //
+            // Don't do this in develop so people remember to run yarn i18n.
+            return { translated: text, isFallback: true };
+        }
         return { translated: fallbackTranslated, isFallback: true };
     }
     return { translated };

test/components/views/settings/__snapshots__/KeyboardShortcut-test.tsx.snap

@@ -32,7 +32,7 @@ exports[`KeyboardShortcut doesn't render same modifier twice 1`] = `
     >
       <kbd>
 
-        missing translation: en|Ctrl
+        Ctrl
 
       </kbd>
       +
@@ -70,7 +70,7 @@ exports[`KeyboardShortcut doesn't render same modifier twice 2`] = `
     >
       <kbd>
 
-        missing translation: en|Ctrl
+        Ctrl
 
       </kbd>
       +
@@ -95,7 +95,7 @@ exports[`KeyboardShortcut renders alternative key name 1`] = `
 >
   <kbd>
 
-    missing translation: en|Page Down
+    Page Down
 
   </kbd>
   +

test/components/views/settings/tabs/user/__snapshots__/KeyboardUserSettingsTab-test.tsx.snap

@@ -8,7 +8,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
     <div
       className="mx_SettingsTab_heading"
     >
-      missing translation: en|Keyboard
+      Keyboard
     </div>
     <KeyboardShortcutSection
       category={
@@ -30,7 +30,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
         <div
           className="mx_SettingsTab_subheading"
         >
-          missing translation: en|Composer
+          Composer
         </div>
         <div>
 
@@ -59,7 +59,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
                   >
                     <kbd>
 
-                      missing translation: en|Ctrl
+                      Ctrl
 
                     </kbd>
                     +
@@ -103,7 +103,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
                   >
                     <kbd>
 
-                      missing translation: en|Ctrl
+                      Ctrl
 
                     </kbd>
                     +
@@ -145,7 +145,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
         <div
           className="mx_SettingsTab_subheading"
         >
-          missing translation: en|Navigation
+          Navigation
         </div>
         <div>
 
@@ -173,7 +173,7 @@ exports[`KeyboardUserSettingsTab renders list of keyboard shortcuts 1`] = `
                   >
                     <kbd>
 
-                      missing translation: en|Enter
+                      Enter
 
                     </kbd>
                   </KeyboardKey>

test/i18n-test/languageHandler-test.tsx

@@ -27,6 +27,10 @@ import {
 import { stubClient } from '../test-utils';
 
 describe('languageHandler', function() {
+    /*
+      See /__mocks__/browser-request.js/ for how we are stubbing out translations
+      to provide fixture data for these tests
+     */
     const basicString = 'Rooms';
     const selfClosingTagSub = 'Accept <policyLink /> to continue:';
     const textInTagSub = '<a>Upgrade</a> to your own domain';
@@ -35,6 +39,7 @@ describe('languageHandler', function() {
 
     type TestCase = [string, string, Record<string, unknown>, Record<string, unknown>, TranslatedString];
     const testCasesEn: TestCase[] = [
+        // description of the test case, translationString, variables, tags, expected result
         ['translates a basic string', basicString, {}, undefined, 'Rooms'],
         [
             'handles plurals when count is 0',
@@ -217,4 +222,17 @@ describe('languageHandler', function() {
             });
         });
     });
+
+    describe('when languages dont load', () => {
+        it('_t', async () => {
+            const STRING_NOT_IN_THE_DICTIONARY = "a string that isn't in the translations dictionary";
+            expect(_t(STRING_NOT_IN_THE_DICTIONARY, {}, undefined)).toEqual(STRING_NOT_IN_THE_DICTIONARY);
+        });
+
+        it('_tDom', async () => {
+            const STRING_NOT_IN_THE_DICTIONARY = "a string that isn't in the translations dictionary";
+            expect(_tDom(STRING_NOT_IN_THE_DICTIONARY, {}, undefined)).toEqual(
+                <span lang="en">{ STRING_NOT_IN_THE_DICTIONARY }</span>);
+        });
+    });
 });