Deleting lambda function make gloo crash because of discovery

[asayah]

Behavior:

We're using invalid route replacement, which is working great for missing upstreams and just returns a custom 404. However, we just had an incident where someone deleted a discovered AWS lambda function in nonprod. Discovery updated the aws-upstream and removed the function name. We had a Virtual Service defined with a route to that function. This then caused complete failure until we deleted that virtual service.

Our proxies all failed on a restart and a glooctl check gave the following error, where run-ecs-task-development was our deleted lambda function
Checking virtual services... Found rejected virtual service: gloo-system run-ecs-task-dot-development
Reason: 1 error occurred:
* Route Error: ProcessingError. Reason: *aws.plugin: unknown function run-ecs-task-development

Expected behavior

Steps to reproduce:
Delete lambda function, with discovery on