Fix: ICE with expanded code #6105

[Tanjaint21]

• Closes rustfmt ICE with expanded code #6105
• Closes ICE: unreachable src/tools/rustfmt/src/expr.rs:407:13 #5885

This is my first pull request 🎉
In this, I am fixing this issue as per suggested by @ytmimi
Thank You.

[ytmimi]

@Tanjaint21 thanks for helping out with this one. When you have a moment could you add the code snippet listed in #6105 (comment) as a test case.

It would also be great if you could add a test case for the code snippet in #5885 as I believe that we should no longer panic when reformatting that macro.

[Tanjaint21]

Hi @ytmimi, I have added the test cases for both #5885 and #6105

[ytmimi]

Awesome! one last ask. When you get a second can you add these new files to this test. I've been adding test cases here to prevent any regressions.

[ytmimi]

Thanks again for your help on this one, and cheers on your first contribution to rustfmt 🎉

[ojeda]

Thanks for fixing those!