fix: rare case when non-last task errors and finishes last

lib/index.js

@@ -138,6 +138,7 @@ module.exports = class Q extends EventEmitter {
         } else {
           self.emit('error', err);
         }
+        self._next2();
         self._next1();
         if (self.active === 0) { self.emit('drain'); }
         return;
@@ -195,7 +196,6 @@ module.exports = class Q extends EventEmitter {
       if (this.active === 0) { this.emit('drain'); }
     });
     this.worker2.apply(null, task.args);
-    this._next2();
   }
 
 

test/error-test.js

@@ -35,6 +35,33 @@ describe('Worker 1 calls callback with error', () => {
       q.push(1);
     });
   });
+
+  describe('Later task finishes before errored task', () => {
+    it('All task finish', (done) => {
+      var otherCallback, errored;
+      var q = new Q((a, callback) => setTimeout(() => {
+        console.log('worker1', a);
+        if (a === 1) {
+          otherCallback = callback;
+        } else if (a === 2) {
+          callback(null, a);
+          otherCallback(new Error('thing'), a);
+        }
+      }), (a, callback) => {
+        console.log('worker2', a, q.active);
+        setTimeout(callback);
+      });
+      q.on('error', () => {
+        errored = true;
+      });
+      q.on('drain', () => {
+        assert.ok(errored);
+        done();
+      });
+      q.push(1);
+      q.push(2);
+    });
+  });
 });
 
 describe('Worker 2 calls callback with error', () => {