fix(LogCollector): Add stack trace to errors.

lib/LogCollector.js

@@ -141,12 +141,14 @@ logLevel /* timestamp, arg2, arg3, arg4... */) {
     for (var i = 1, len = arguments.length; i < len; i++) {
         var arg = arguments[i];
 
-        if (this.stringifyObjects && typeof arg === 'object') {
+        if (arg instanceof Error) {
+            msg += arg.toString() + ': ' + arg.stack;
+        } else if (this.stringifyObjects && typeof arg === 'object') {
         // NOTE: We were trying to stringify all error logs before but because of a bug that we were getting the keys
         // of the log levels which are all with upper case and comparing it with the keys which are all lower case we
         // were never actually strinfying the error logs. That's why I've removed the check for error logs here.
         // NOTE: The non-enumerable properties of the objects wouldn't be included in the string after JSON.strigify.
-        // For example Error instance will be translated to '{}'. So I think we have to eventually do something better
+        // For example Map instance will be translated to '{}'. So I think we have to eventually do something better
         // for parsing the arguments. But since this option for strigify is part of the public interface and I think
         // it could be useful in some cases I will it for now.
             msg += this.stringify(arg);