Style/MissingElse crash

[gerry3]

I'm using master - 0.29.1 (using Parser 2.2.0.3, running on ruby 2.2.0 x86_64-darwin14)

The Style/MissingElse cop causes the offense report to crash:

<file>.rb:9:5: C: if condition requires an else-clause.
undefined method `source_line' for #<Parser::Source::Map::Condition:0x007fde525c2140>
<path>/.rvm/gems/ruby-2.2.0@<gemset>/bundler/gems/rubocop-f52bc7e2ec4b/lib/rubocop/formatter/clang_style_formatter.rb:15:in `block in report_file'

The fix seems to be to pass :expression as the second argument to add_offense (instead of node.location). I will submit a PR with the fix soon.

I noticed that when an exception occurs during inspection, it's caught and a message is displayed (An error occurred while <cop> cop was inspecting <file>.). Should something similar be done during reporting? Or is there another way we could catch an issue like this ahead of time? Is there a type of spec that tests reporting missing for this cop?