Bug 889526 - Improve reportError so that it will add a stack trace if one is available; r=past

toolkit/devtools/server/actors/script.js

@@ -280,10 +280,7 @@ ThreadActor.prototype = {
       resolve(onPacket(packet)).then(this.conn.send.bind(this.conn));
       return this._nest();
     } catch(e) {
-      let msg = "Got an exception during TA__pauseAndRespond: " + e +
-                ": " + e.stack;
-      Cu.reportError(msg);
-      dumpn(msg);
+      reportError(e, "Got an exception during TA__pauseAndRespond: ");
       return undefined;
     }
   },
@@ -1241,8 +1238,7 @@ ThreadActor.prototype = {
       this.conn.send(packet);
       return this._nest();
     } catch(e) {
-      Cu.reportError("Got an exception during TA_onExceptionUnwind: " + e +
-                     ": " + e.stack);
+      reportError(e, "Got an exception during TA_onExceptionUnwind: ");
       return undefined;
     }
   },
@@ -1490,10 +1486,7 @@ SourceActor.prototype = {
           source: aSourceGrip
         };
       }, (aError) => {
-        let msg = "Got an exception during SA_onSource: " + aError +
-          "\n" + aError.stack;
-        Cu.reportError(msg);
-        dumpn(msg);
+        reportError(aError, "Got an exception during SA_onSource: ");
         return {
           "from": this.actorID,
           "error": "loadSourceError",
@@ -2924,8 +2917,14 @@ function convertToUnicode(aString, aCharset=null) {
 
 /**
  * Report the given error in the error console and to stdout.
+ *
+ * @param Error aError
+ *        The error object you wish to report.
+ * @param String aPrefix
+ *        An optional prefix for the reported error message.
  */
-function reportError(aError) {
-  Cu.reportError(aError);
-  dumpn(aError.message + ":\n" + aError.stack);
+function reportError(aError, aPrefix="") {
+  let msg = prefix + aError.message + ":\n" + aError.stack;
+  Cu.reportError(msg);
+  dumpn(msg);
 }