refactor for tautological condition non-nil not equal to nil

[sejima1105]

Description

Refactoring for tautological condition non-nil != nil

Checklist

Please check if applicable

• Tests have been added (if applicable, ie. when operator codes are added or modified)
• Relevant docs have been added or modified (if applicable, ie. when new features are added or current features are modified)

Relevant issue https://github.com/st-tech/sre-dept-issues/issues/7361

Operation check

I ran the sample scenario and confirmed that no errors occurred.

[kane8n]

When gatling is nil, the nil pointer access is panicked, so here is the case

if gatling ! = nil && gatling.Spec.TestScenarioSpec.SimulationData && len(gatling.Spec.TestScenarioSpec.SimulationData) > 0

is a good choice here.
The zero value of map is nil, so the nil check of SimulationData is left as it is.

[sejima1105]

Thank you for the review!

It is indeed a very good idea.
However, I thought that using this approach might change the existing behavior if gatling is nil.
For example, if gatling is nil in the createVolumesForCR function, no processing is performed and error is returned as nil.

To prevent this, I think it would be better to check for nil at the beginning of the function and return an error at that point.
What do you think?

Here's what I have in mind to add at the beginning of the function.

if gatling == nil {
    return errors.New("gatling is nil")
}