Fix Promise.map unhandled rejections (#1487)

src/map.js

@@ -23,14 +23,15 @@ function MappingPromiseArray(promises, fn, limit, _filter) {
     this._limit = limit;
     this._inFlight = 0;
     this._queue = [];
-    async.invoke(this._asyncInit, this, undefined);
+    this._asyncQueue = [];
+    this._init$(undefined, RESOLVE_ARRAY);
+    if (!this._isResolved() && this._asyncQueue.length > 0) {
+        async.invoke(this._drainAsyncQueue, this, this._asyncQueue);
+    }
+    this._asyncQueue = undefined;
 }
 util.inherits(MappingPromiseArray, PromiseArray);
 
-MappingPromiseArray.prototype._asyncInit = function() {
-    this._init$(undefined, RESOLVE_ARRAY);
-};
-
 // The following hack is required because the super constructor
 // might call promiseFulfilled before this.callback = fn is set
 //
@@ -60,6 +61,11 @@ MappingPromiseArray.prototype._promiseFulfilled = function (value, index) {
             if (this._isResolved()) return true;
         }
     } else {
+        if (this._asyncQueue !== undefined) {
+            this._asyncQueue.push([value, index]);
+            return false;
+        }
+
         if (limit >= 1 && this._inFlight >= limit) {
             values[index] = value;
             this._queue.push(index);
@@ -144,6 +150,15 @@ MappingPromiseArray.prototype._filter = function (booleans, values) {
     this._resolve(ret);
 };
 
+MappingPromiseArray.prototype._drainAsyncQueue = function (queue) {
+    var len = queue.length;
+    var item;
+    for (var i = 0; i < len && !this._isResolved(); ++i) {
+        item = queue[i];
+        this._promiseFulfilled(item[0], item[1]);
+    }
+};
+
 MappingPromiseArray.prototype.preservedValues = function () {
     return this._preservedValues;
 };