Lexer deadlocks on incorrect template instead of erroring

[krzysztofzablocki]

Scenario:

If a tag is not closed properly
e.g.

{{ something

Expectation:

Error is thrown or processing is finished without result.

What happens:

https://github.com/kylef/Stencil/blob/master/Sources/Lexer.swift#L27 deadlocks

// cc @ilyapuchka

[krzysztofzablocki]

I think this can be fixed by simply adding content = "" here: https://github.com/kylef/Stencil/blob/master/Sources/Lexer.swift#L93

That will break the deadlock and just ignore the given tag? but I didn't analyse exactly how Stencil is implemented so I might be off track