fix(error): Polish --flag=bad-value error

[epage]

This error was untested and didn't fit the style of our other errors

error: The value 'value' was provided to '--flag' but it wasn't expecting any more values

example --other <path>...

For more information try '--help'

• It should show a usage type
• It should show the flag in the usage so people can scan more quickly for what is wrong

This supersedes #4268