patternMap.entries.singleWhere throws state error when multiple regexps match

[TonyDowney]

When the patternMap has two RegExp that both match the same String, this library throws a state error on patternMap.entries.singleWhere. I'd suggest replacing it with firstWhere and documenting the behaviour when multiple RegExp match.

[micazi]

Will work it out in the next version or if you'd like to fork and contribute i would highly appreciate it, Thank you! 😄