feat: print exceptions to stderr (ESPTOOL-731)

[Massimiliano-solutiontech]

Now the exceptions are printed out in the stderr instead of stdout. That could be a breaking change for some users so here two considerations:

1. make this feature opt-in by a parameter or via esptool.cfg
2. the existing scripts can redirect the stderr to stdout by doing esptool.py flash_id &> stdout+stderr.txt

I found this open issue #888 but in my opinion this change can be merged in the current version (4.7)

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[radimkarnis]

Hello @Massimiliano-solutiontech,
thank you for your contribution!

Unfortunately, this cannot be merged at this moment, as it is a breaking change. It would require a new major release (v5.0). #888 is a duplicate and it's planned to be done as a part of the next major release.

make this feature opt-in by a parameter or via esptool.cfg

This sounds like a reasonable solution in the meantime. Would you be interested in doing that as a part of this PR?

the existing scripts can redirect the stderr to stdout by doing esptool.py flash_id &> stdout+stderr.txt

Unfortunately, this means it is still a breaking change if the existing scripts have to be changed.

[Massimiliano-solutiontech]

This sounds like a reasonable solution in the meantime. Would you be interested in doing that as a part of this PR?

Yes, in the next few days I'll update this PR

Thanks

[Massimiliano-solutiontech]

Hi @radimkarnis,
I did the modifications now the default behavior is restored (errors are printed to stdout)

Now you can redirect errors to stderr by:

• adding --redirect-errors arg (eg. esptool.py --redirect-errors flash_id
• adding redirect_errors = true to the esptool.cfg file

Let me know if the name of the arg fits and/or if the implementation that I did is ok

[radimkarnis]

Hello @Massimiliano-solutiontech,

thanks for the implementation!

I will ask you to kindly remove the --redirect-errors arg. We try to keep esptool options and arguments as lean as possible. The configuration file is enough to activate this feature until it's made default in the next major release.

[Massimiliano-solutiontech]

@radimkarnis done

[radimkarnis]

Hi @Massimiliano-solutiontech,
thanks for the update and sorry for this taking so long - there were some ongoing internal discussions about this.

I am sorry to change our opinion, but we have decided not to implement this as a configurable option, because:

1. The config file is used to set internal variables related to the serial communication, not the behavior of the tool itself.
2. We would have to introduce versioning to the config file because of this change (the redirect_errors option would be present only in this version of esptool).
3. Printing to stderr will be properly implemented and set as default in the next major release (Stderr empty when calling esptool with subprocess.Popen (ESPTOOL-696) #888).

I hope you understand that we need to keep the tools as lean as possible because every new option decreases maintainability.

Thanks for your work on this, it is appreciated!