inconsistency in error handling and logging in match command

The match command currently logs errors when it should just log warnings (eg. when a debian match cannot be even searched because there is no upstream package to compare, or there are too many upstream packages and we can't tell which is the main one, etc.)

Furthermore, exception handling between nested methods is inconsistent and may lead to confusing log messages.

Instead, we should have consistent logging, and log errors only when something went wrong, and not when a match can't be found.