Handle syntax error in Ripper
Created by: yujinakayama
Ripper might fail to parse a Ruby source even if the current runtime parsed it properly, because some versions of JRuby have different implementation of runtime parser and Ripper parser.
https://github.com/jruby/jruby/issues/2427
So we handle the syntax error in Ripper and fall back to the simple single line extraction in that case.