If the working directory for a command was missing (usually due to
forgetting to run 'west update'), you'd get a FileNotFoundError
exception along with a cryptic error like
'git' not found
Only catch OSError instead (which is a base class of FileNotFoundError),
and always show the exception message. It makes it clear that it's the
working directory that's missing.
Add some other misc. improvements too:
- Turn stderr output from external commands into a warning instead of
an error
- Add err() and warn() helpers
- Include the command name in messages
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>
5372dedf2f