Fix reader/writer.closed docs for web streams

Author: MattiasBuelens

doc/api/webstreams.md

@@ -425,7 +425,8 @@ added: v16.5.0
 -->
 
 * Type: {Promise} Fulfilled with `undefined` when the associated
-  {ReadableStream} is closed or this reader's lock is released.
+  {ReadableStream} is closed, or rejected when the stream errors or
+  this reader's lock is released.
 
 #### `readableStreamDefaultReader.read()`
 
@@ -552,7 +553,8 @@ added: v16.5.0
 -->
 
 * Type: {Promise} Fulfilled with `undefined` when the associated
-  {ReadableStream} is closed or this reader's lock is released.
+  {ReadableStream} is closed, or rejected when the stream errors or
+  this reader's lock is released.
 
 #### `readableStreamBYOBReader.read(view)`
 
@@ -903,8 +905,8 @@ added: v16.5.0
 -->
 
 * Type: A promise that is fulfilled with `undefined` when the
-  associated {WritableStream} is closed or this writer's lock is
-  released.
+  associated {WritableStream} is closed, or is rejected when the
+  stream errors or this writer's lock is released.
 
 #### `writableStreamDefaultWriter.desiredSize`