Improve log around the request handlers

Author: bigmontz

src/internal/bolt/response-handler.js

@@ -35,6 +35,7 @@ const NO_OP_OBSERVER = {
   onCompleted: NO_OP,
   onError: NO_OP
 }
+let requestHandlerNextId = 0
 
 /**
  * Treat the protocol responses and notify the observers
@@ -84,6 +85,7 @@ export default class ResponseHandler {
       },
       observer
     )
+    this._requestHandlerId = requestHandlerNextId++
   }
 
   handleResponse (msg) {
@@ -102,6 +104,11 @@ export default class ResponseHandler {
         }
         try {
           const metadata = this._transformMetadata(payload)
+          if (!this._currentObserver) {
+            this._log.trace(
+              `${this._requestHandlerId}.handleResponse(SUCCESS) current observer is undefined`
+            )
+          }
           this._currentObserver.onCompleted(metadata)
         } finally {
           this._updateCurrentObserver()
@@ -152,6 +159,12 @@ export default class ResponseHandler {
    */
   _updateCurrentObserver () {
     this._currentObserver = this._pendingObservers.shift()
+    if (!this._currentObserver) {
+      console.trace(
+        `${this._requestHandlerId}._updateCurrentObserver to`,
+        this._currentObserver
+      )
+    }
   }
 
   _queueObserver (observer) {
@@ -160,6 +173,10 @@ export default class ResponseHandler {
     observer.onError = observer.onError || NO_OP
     observer.onNext = observer.onNext || NO_OP
     if (this._currentObserver === undefined) {
+      console.trace(
+        `${this._requestHandlerId}._queueObserver, this._currentObserver=`,
+        observer
+      )
       this._currentObserver = observer
     } else {
       this._pendingObservers.push(observer)