_level_value used logging.getLevelName(name), which returns the string 'Level XXX'
for an unknown name; that string then reached setLevel() and raised ValueError,
violating the 'never crashes the app over logging' contract. validate the result is
an int and fall back to INFO otherwise.
verified: level='BOGUS' -> INFO (no crash); 'DEBUG' and int levels still honored.
Signed-off-by: disqualifier <dev@disqualifier.me>