`yard stats --fail-on-warning` doesn't fail on warnings

[ojab]

Steps to reproduce

class Xxx
  # @param [xxx]
  def self.x
    puts 'xxx'
  end
end

$ yard doc --fail-on-warn .
[warn]: @param tag has unknown parameter name:  
    in file `xxx.rb' near line 3
…
$ echo $?
1
$ yard stats --fail-on-warn .
[warn]: @param tag has unknown parameter name:  
    in file `xxx.rb' near line 3
…
$ echo $?
0

Environment details:

• OS: linux x64_64
• Ruby version (ruby -v): ruby 3.0.1p64 (2021-04-05 revision 0fb782ee38) [x86_64-linux]
• YARD version (yard -v): yard 0.9.26
• Relevant software dependency/versions:
  • [Any 3rd party libs required to reproduce, omit if none]

I have read the Contributing Guide.

[lsegal]

This seems like a bug in documentation for yard stats --help. The --fail-on-warning option should not be listed as part of this command; due to internal structure of YARD CLI commands, these two commands share a common base, but not all options are shared.

In this case --fail-on-warning is defined strictly in yard doc and using it in another command should be undefined behavior. The fix here should be to remove the option from documentation in yard stats --help, however the commands above are expected behavior (though the latter command should warn about the unrecognized option).

[lsegal]

Actually given the simplicity of allowing yard stats to respect warning failure, it's probably easier to add it there.