Bug 1649168 - Fix gecko decision task failure. r=fix CLOSED TREE

taskcluster/taskgraph/transforms/scriptworker_canary.py

@@ -18,7 +18,7 @@ transforms = TransformSequence()
 
 @transforms.add
 def build_command(config, jobs):
-    scriptworkers = config.params["try_task_config"].get("scriptworker-canary-workers")
+    scriptworkers = config.params["try_task_config"].get("scriptworker-canary-workers", [])
     # Filter the list of workers to those we have configured a set of canary
     # tasks for.
     scriptworkers = [