Fix Bad Field type panic

[darklam]

Fixes Or Enhances

Fixes #907 (and possibly others?)

At first I found it weird that the required_if affected the behavior of the gte tag, but after some debugging it seems that the condition runValidationWhenNil is not checked for each field tag, but only for the first one.
In this case it was set to true for the required_if tag, but set to false for gte, so when the required_if preceded the gte tag it meant that the field was incorrectly validated through gte even when it was nil.

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• Tests exist or have been written that cover this particular change.

@go-playground/validator-maintainers

[coveralls]

coverage: 73.933% (+0.03%) from 73.903%
when pulling d015ea4 on darklam:fix-bad-field-type-panic
into 84254ae on go-playground:master.

[darklam]

Not very familiar with the errors in this library, so I just went by what was used in the other instance where the runValidationWhenNil is checked and could be entirely wrong 😄

[deankarn]

Thanks fro the PR @darklam

I will have to think hard on if this could cause any breaking side-effects, see here for details.

[darklam]

Thanks fro the PR @darklam

I will have to think hard on if this could cause any breaking side-effects, see here for details.

Yes, agreed that this should be scrutinized a lot regarding breaking changes before merging. I'm happy to add more test cases if there are any specific ones coming to mind.
Also, my first thought was indeed to change some baked ins like gte to handle nil cases, but it didn't seem like the way to go because it became quite repetitive.
I think that the check for that should happen before getting to these validators (as the original intention seems to be with the runValidationWhenNil flag), but of course this is not an informed opinion as I'm quite new with the codebase 😄