avoid interacting with nil mutatedWfs

[ckiosidis]

Signed-off-by: Babis Kiosidis [email protected]

goroutine 1299 [running]:
github.com/flyteorg/flytepropeller/pkg/controller.(*Propeller).Handle(0xc0010bcf00, {0x29ee0d8, 0xc2188e2720}, {0xc0009b8140, 0x12}, {0xc0009b8153, 0x8})
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/handler.go:251 +0xd76
github.com/flyteorg/flytepropeller/pkg/controller.(*WorkerPool).processNextWorkItem.func1(0xc001024870, 0xc1f8f1ff28, {0x1ff6080?, 0xc000cbeec0})
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/workers.go:88 +0x510
github.com/flyteorg/flytepropeller/pkg/controller.(*WorkerPool).processNextWorkItem(0xc001024870, {0x29ee0d8, 0xc2188e2720})
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/workers.go:99 +0xf1
github.com/flyteorg/flytepropeller/pkg/controller.(*WorkerPool).runWorker(0x29ee0d8?, {0x29ee0d8, 0xc2192d2d80})
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/workers.go:115 +0xbd
github.com/flyteorg/flytepropeller/pkg/controller.(*WorkerPool).Run.func1()
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/workers.go:150 +0x59
created by github.com/flyteorg/flytepropeller/pkg/controller.(*WorkerPool).Run
	/go/pkg/mod/github.com/flyteorg/[email protected]/pkg/controller/workers.go:147 +0x285

TL;DR

when there is an error in the mutatedWf, the handler should avoid interacting with the nil obj

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

How did you fix the bug, make the feature etc. Link to any design docs etc

Tracking Issue

Remove the 'fixes' keyword if there will be multiple PRs to fix the linked issue

fixes https://github.com/flyteorg/flyte/issues/

Follow-up issue

NA
OR
https://github.com/flyteorg/flyte/issues/

[codecov]

Codecov Report

Merging #477 (0ce86ec) into master (fb78f46) will increase coverage by 0.00%.
The diff coverage is 100.00%.