Fix for handling empty code block in doc comment

[davidBar-On]

Fixes #5234

Suggested fix is by trimming the code block, as discussed in (now obsolete) PR #4902.

[ytmimi]

Thank you for opening up this new PR!

[tgross35]

Related open PR: #5235

[ytmimi]

@tgross35 thanks, I was aware of the other PR and was planning on closing it. Will do so now

[calebcartwright]

While I think there's little rationale and utility in practice for having a doc comment codeblock with nothing but whitespace, and obviously a panic is unacceptable, but do we feel that trimming that whitespace is the correct/desirable behavior?

[tgross35]

Imho I generally expect rustfmt to eliminate unneeded whitespace, so I would say yes. This would be consistent with what happens when it gets a file with no content and only blank lines - it removes them.

[calebcartwright]

Imho I generally expect rustfmt to eliminate unneeded whitespace, so I would say yes. This would be consistent with what happens when it gets a file with no content and only blank lines - it removes them.

Yeah that's a fair way of looking at it 👍