No more unwraps or expects

[cole-h]

Also, there should probably be some better error handling -- would be nice if there was some way to differentiate between fatal and not-so-fatal errors.

Originally posted by @cole-h in #1 (comment)

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If we have a lot of potentially-non-fatal errors, maybe we could change return signatures to be Result<(), Vec<Error>>, and report all non-fatal errors at the end?

[cole-h]

Another place to check:

This return type is a bit weird. It might be worth looking out for ways to improve this, like an enum of DetectionResult { ExecError, ParseError, Ok } -- but not sure, and definitely not asking you to do it now.

Originally posted by @grahamc in #1 (comment)