Now able to track error handler registration via instance properties

javascript/ql/src/Quality/UnhandledStreamPipe.ql

@@ -227,6 +227,13 @@ private predicate hasErrorHandlerRegistered(PipeCall pipeCall) {
         stream = base.getAPropertyRead(propName) and
         base.getAPropertyRead(propName).getAMethodCall(_) instanceof ErrorHandlerRegistration
       )
+      or
+      exists(DataFlow::PropWrite propWrite, DataFlow::SourceNode instance |
+        propWrite.getRhs().getALocalSource() = stream and
+        instance = propWrite.getBase().getALocalSource() and
+        instance.getAPropertyRead(propWrite.getPropertyName()).getAMethodCall(_) instanceof
+          ErrorHandlerRegistration
+      )
     )
   )
   or

javascript/ql/test/query-tests/Quality/UnhandledStreamPipe/test.expected

@@ -16,5 +16,4 @@
 | tst.js:44:5:44:40 | wrapper ... Stream) | Stream pipe without error handling on the source stream. Errors won't propagate downstream and may be silently dropped. |
 | tst.js:52:5:52:37 | source. ... Stream) | Stream pipe without error handling on the source stream. Errors won't propagate downstream and may be silently dropped. |
 | tst.js:59:18:59:39 | stream. ... Stream) | Stream pipe without error handling on the source stream. Errors won't propagate downstream and may be silently dropped. |
-| tst.js:73:5:73:40 | wrapper ... Stream) | Stream pipe without error handling on the source stream. Errors won't propagate downstream and may be silently dropped. |
 | tst.js:111:5:111:26 | stream. ... Stream) | Stream pipe without error handling on the source stream. Errors won't propagate downstream and may be silently dropped. |

javascript/ql/test/query-tests/Quality/UnhandledStreamPipe/tst.js

@@ -70,7 +70,7 @@ class StreamWrapper2 {
 function zip5() {
     const zipStream = createWriteStream(zipPath);
     let wrapper = new StreamWrapper2();
-    wrapper.outputStream.pipe(zipStream); // $SPURIOUS:Alert
+    wrapper.outputStream.pipe(zipStream);
     zipStream.on('error', e);
 }