I narrowed down to SyntaxError because if trim option is not present, SyntaxError is raised. It is an explicite sign if actual code cannot parse the `.rspec` file. No other way to detect missing trim options, sadly.

However, this test code is tests trim option existence, not the quality of the actual code parsing code. If another error is raised, it should be covered by another code, not this.

But if you still want, I can remove the concrete error class.