fixes

docs/tutorials/handlers-tutorial.md

@@ -20,13 +20,13 @@ Each associates a function with an HTTP URL.
 
 ### Handlers
 
-A function annotated with an endpoint decorator but no other decorators like is called a _handler_ and must take a [`HandlerContext`](..) as its first argument, like in the example above.
+A function annotated with an endpoint decorator but no other decorators is called a _handler_ and must take a [`HandlerContext`](..) as its first argument, like in the example above.
 Handlers can invoke other functions and directly access HTTP requests and responses.
 However, Operon makes no guarantees about handler execution: if a handler fails, it is not automatically retried.
 You should use handlers when you need to access HTTP responses directly or when you're doing a lightweight task that doesn't need the strong guarantees of transactions and workflows.
 
-You don't need a handler to serve a transaction, workflow, or communicator from an HTTP URL.
-You can also annotate your function with an endpoint decorator in addition to its [`@OperonTransaction`](../api-reference/decorators#operontransaction), [`@OperonWorkflow`](../api-reference/decorators#operonworkflow), or [`@OperonCommunicator`](../api-reference/decorators#operoncommunicator) decorator.
+You don't need a handler function to serve a transaction, workflow, or communicator from an HTTP URL.
+You can also annotate your existing function with an endpoint decorator in addition to its [`@OperonTransaction`](../api-reference/decorators#operontransaction), [`@OperonWorkflow`](../api-reference/decorators#operonworkflow), or [`@OperonCommunicator`](../api-reference/decorators#operoncommunicator) decorator.
 For example (from our [quickstart](..)):
 
 ```javascript
@@ -48,24 +48,25 @@ Any Operon method invoked via HTTP request can access the raw request from its `
 If a function has arguments other than its context, Operon attempts to automatically parse them from the HTTP request.
 Arguments can be parsed from three places:
 
-1. From a URL query string parameter with the same name.
-2. From an HTTP body field with the same name.
-3. From an HTTP path parameter, if one is specified in the decorated URL.
+1. From a URL query string parameter with the same name (by default, only for `GET`).
+2. From an HTTP body field with the same name (by default, only for `POST`).
+3. From an URL path parameter, if one is specified in the decorated URL.
 
 Input parsing can be configured using the [`@ArgSource`](../api-reference/decorators#argsource) parameter decorator.
 
-By default, Operon automatically validates parsed inputs, returning an error if a function is missing required inputs or if the input received is of a different type than specified in the method signature. 
+By default, Operon automatically validates parsed inputs, throwing an error if a function is missing required inputs or if the input received is of a different type than specified in the method signature. 
 Validation can be turned off at the class level using [`@DefaultArgOptional`](..) or controlled at the parameter level using [`@ArgRequired`](..) and [`@ArgOptional`](..).
 
 ### Outputs and HTTP Responses
 
-By default, if an Operon function invoked via HTTP request returns successfuly, its return value is sent in the body of the HTTP response with status code `200`.
+By default, if an Operon function invoked via HTTP request returns successfuly, its return value is sent in the HTTP response body with status code `200` (or `204` if nothing is returned).
 If the function throws an exception, the error message is sent in the response body with a `400` or `500` status code.
+If the error contains a `status` field (we provide [`OperonResponseError`](..) for this purpose), Operon uses that status code instead.
 
 If you need custom HTTP response behavior, you can use a handler to access the HTTP response directly.
-Operon uses [Koa](https://koajs.com/) for HTTP serving internally, so the raw response can be accessed via the `.koaContext.response` field of [`HandlerContext`](..), which returns a [Koa response](https://koajs.com/#response).
+Operon uses [Koa](https://koajs.com/) for HTTP serving internally, so the raw response can be accessed via the `.koaContext.response` field of [`HandlerContext`](..), which provides a [Koa response](https://koajs.com/#response).
 
 ### Middleware
 
 Operon supports running custom [Koa](https://koajs.com/) middleware for serving HTTP requests.
-Middleware is configured at the class level through the [`@KoaMiddleware`](../api-reference/decorators@koamiddleware) decorator.
+Middleware is configured at the class level through the [`@KoaMiddleware`](../api-reference/decorators#koamiddleware) decorator.