RunCommand: WA no longer runs with no workloads specs

Previously if no worklaod specs were loaded, WA would still start instruments
and then go immediately to the teardown stage. This no longer happens.

wlauto/commands/run.py

@@ -77,6 +77,9 @@ class RunCommand(Command):
             agenda = Agenda(args.agenda)
             settings.agenda = args.agenda
             shutil.copy(args.agenda, settings.meta_directory)
+
+            if len(agenda.workloads) == 0:
+                raise ConfigError("No workloads specified")
         elif '.' in args.agenda or os.sep in args.agenda:
             raise ConfigError('Agenda "{}" does not exist.'.format(args.agenda))
         else: