fix(errormapping): Don't try to decode to unicode if already unicode
fix(errormapping): Don't try to decode to unicode if already unicode

Fixes SENTRY-6SR

mvaled/sentry,beeftornado/sentry,mvaled/sentry,mvaled/sentry,mvaled/sentry,mvaled/sentry,mvaled/sentry,beeftornado/sentry,beeftornado/sentry