Fixes async task from node error

Fixes #215

packages/base/source/conversions/nodeback-to-task.js

@@ -22,7 +22,7 @@ const { task } = require('folktale/concurrency/task');
 
 const nodebackToTask = fn => (...args) => (
   task(r =>
-    fn(...args, (err, data) => err ? r.reject(err) : r.resolve(data))
+    fn(...args, (err, data) => r.isCancelled ? undefined : err ? r.reject(err) : r.resolve(data))
   )
 );
 

test/source/specs/base/concurrency/task.js

@@ -7,6 +7,7 @@
 //
 //----------------------------------------------------------------------
 
+const assert = require('assert');
 const { property } = require('jsverify');
 const env = require('../environment');
 
@@ -574,5 +575,14 @@ describe('Data.Task', () => {
       const task = convertedFn('test');
       await task.run().promise().catch(e => $ASSERT(e === error));
     });
+
+    it('Should allow rejecting more than once', async () => {
+        const error = 'failed';
+        const fn = (str, cb) => setTimeout(() => cb(error, ''), 0);
+        const convertedFn = Task.fromNodeback(fn);
+        const task1 = convertedFn('test');
+        const task2 = convertedFn('test');
+        assert.doesNotThrow(async () => await task1.and(task2).run().promise());
+    });
   });
 });