A thread in the runtime but with the DONE status is not active

return false from isActiveThread if thread's status is done even when
its contained in the runtime threads list. As it is done, the thread
will not be run until either its replaced by a new copy of the thread
or the thread is removed from the list and another is added at a later
time.

src/engine/runtime.js

@@ -825,7 +825,11 @@ class Runtime extends EventEmitter {
      * @return {boolean} True if the thread is active/running.
      */
     isActiveThread (thread) {
-        return this.threads.indexOf(thread) > -1;
+        return (
+            (
+                thread.stack.length > 0 &&
+                thread.status !== Thread.STATUS_DONE) &&
+            this.threads.indexOf(thread) > -1);
     }
 
     /**