"kn service delete" exited with code ZERO when it ran into failure

[zyjiaobj]

Bug report

➜  ~ kn service delete hello
Internal error occurred: failed calling webhook "validation.webhook.serving.knative.dev": Post https://webhook.knative-serving.svc:443/resource-validation?timeout=10s: context deadline exceeded.
➜  ~ echo $?
0
➜  ~ kn service delete hello --no-wait
Internal error occurred: failed calling webhook "validation.webhook.serving.knative.dev": Post https://webhook.knative-serving.svc:443/resource-validation?timeout=10s: context deadline exceeded.
➜  ~ echo $?
0
➜  ~ kn service delete abc
services.serving.knative.dev "abc" not found.
➜  ~ echo $?
0

Expected behavior

I suppose I should get a return code "1" for the delete failure.

Steps to reproduce the problem

Delete n nonexistent ksvc:

➜  ~ kn service delete abc
services.serving.knative.dev "abc" not found.
➜  ~ echo $?
0

kn version

➜  ~ kn version
Version:      v0.16.0
Build Date:   2020-07-15 07:01:17
Git Revision: 5cb78308
Supported APIs:
* Serving
  - serving.knative.dev/v1 (knative-serving v0.16.0)
* Eventing
  - sources.knative.dev/v1alpha2 (knative-eventing v0.16.0)
  - eventing.knative.dev/v1beta1 (knative-eventing v0.16.0)

Knative (serving/eventing) version

v0.16.0

[hemanrnjn]

/assign