fix interactive args cancellation

artiq/language/environment.py

@@ -350,8 +350,9 @@ class HasEnvironment:
         yield namespace
         del namespace.setattr_argument
         argdict = self.__argument_mgr.get_interactive(interactive_arglist, title)
-        for key, value in argdict.items():
-            setattr(namespace, key, value)
+        if argdict is not None:
+            for key, value in argdict.items():
+                setattr(namespace, key, value)
 
     def get_device_db(self):
         """Returns the full contents of the device database."""

artiq/master/databases.py

@@ -144,4 +144,4 @@ class InteractiveArgDB:
         if rid not in self.futures:
             raise ValueError("no experiment with this RID is "
                              "waiting for interactive arguments")
-        self.futures[rid].cancel()
+        self.futures[rid].set_result(None)

artiq/master/worker_impl.py

@@ -222,8 +222,9 @@ class ArgumentManager(ProcessArgumentManager):
         arglist_desc = [(k, p.describe(), g, t)
                         for k, p, g, t in interactive_arglist]
         arguments = ArgumentManager._get_interactive(arglist_desc, title)
-        for key, processor, _, _ in interactive_arglist:
-            arguments[key] = processor.process(arguments[key])
+        if arguments is not None:
+            for key, processor, _, _ in interactive_arglist:
+                arguments[key] = processor.process(arguments[key])
         return arguments