🐛 Fix provider crash when netbox connection is unavailable

[twink0r]

Hi folks!

While writing tests and run make testacc I forgot to change the URL in my local provider configuration and the provider crashes with a SIGSEGV. Some other users already reported this issue (#110).

Cheers

[fbreckle]

I know all contributors love this: Can you please add tests for this? :D

Just run against example.com or so and then expect an error. I'm actually somewhat at a loss on how to exactly do this. Maybe look at https://github.com/hashicorp/terraform-provider-aws/blob/main/internal/provider/provider_test.go

If you don't feel like jumping through this hoop, I can just merge as-is and add tests later.

[twink0r]

I will dig into this later today!

[twink0r]

@fbreckle I added a test for configure the Netbox Provider the to a non-existing URL that broke and let the Provider crash before. It was a nightmare to get this test to work because there is no documentation for this kind of tests. Maybe "someone" should add a test for missing required attributes?

[fbreckle]

I'm not completely sold on having to make a custom configure func for the tests.

I'm not even sure if the version detection functionality is in the correct file, maybe it "belongs" to config.go

However, I find it good enough as is.