fix(macos): crash when custom protocol response is empty

[lucasfernog]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

I found this crash in the streaming example (tauri repo). When the response is empty (e.g. return ResponseBuilder::new().mimetype("text/plain").status(404).body(Vec::new())), the app was crashing with this report:

streaming(13585,0x103b90580) malloc: *** error for object 0x1: pointer being freed was not allocated
streaming(13585,0x103b90580) malloc: *** set a breakpoint in malloc_error_break to debug

This change fixes it, setting freeWhenDone to NO if the response buffer is empty.

[davidarroyo1234]

Turns out it was an empty css file

Thanks, now its opening in release mode..

(Using angular).