Some hidden characters cause the CLI compilation to fail, and also breaks the language-server

[kittaakos]

Describe the bug

Try to compile the attached sketch, it fails:

arduino-cli compile -b arduino:avr:nano ./mysketch

/Users/akos.kitta/Desktop/mysketch/mysketch.ino:11:1: error: stray '\342' in program
 ???
 ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:11:2: error: stray '\200' in program
 ???
  ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:11:3: error: stray '\213' in program
 ??
   ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:13:1: error: stray '\342' in program
 ???
 ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:13:2: error: stray '\200' in program
 ???
  ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:13:3: error: stray '\213' in program
 ??
   ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:28:1: error: stray '\342' in program
 ???
 ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:28:2: error: stray '\200' in program
 ???
  ^
/Users/akos.kitta/Desktop/mysketch/mysketch.ino:28:3: error: stray '\213' in program
 ??
   ^
Error during build: exit status 1

It also breaks the language server:

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[per1234]

@kittaakos do you have any ideas for how this experience could be improved?

This is a common issue, which I have never considered addressing via the tooling, but it's interesting to think about.

Certainly a nice troubleshooting guide that identifies the cause and easiest fix for this class of error would be well worth creating though.

[kittaakos]

If this is the expected behavior from the CLI, there is not much the IDE2 can do. Upstream ref: arduino/arduino-cli#1808

Closing as won't fix.