Added test showing the issue when fixture depends on ordered fixture

[stollr]

This test shows the issue described in #148.

The error handler has to be replaced for the test, because otherwise the code works and the deprecation for the undefined array key does not show up.

Closes #198

[stollr]

I have added a fix to the issue, now, too. I hope it is okay to do it in the same PR.

[stollr]

@derrabus Thanks for your improvement. It is much cleaner indeed.

[greg0ire]

@stollr please run vendor/bin/phpcbf and squash the commits

[stollr]

@greg0ire done

[greg0ire]

Thanks @stollr !