Fix expect_offense when annotations missing
Fix expect_offense when annotations missing

Fix crash in expect_offense where multiple offenses are detected by the
cop by some were not included in the annotated source. For example:

```ruby
expect_offense(<<~RUBY)
  x % 2 == 0
  ^^^^^^^^^^ Replace with `Integer#even?`
  x % 2 != 0
  # second offense missing
RUBY
```

tejasbubane/rubocop,jmks/rubocop,tejasbubane/rubocop,rrosenblum/rubocop,tejasbubane/rubocop,maxjacobson/rubocop,tdeo/rubocop,maxjacobson/rubocop,jmks/rubocop,rrosenblum/rubocop,rrosenblum/rubocop,bbatsov/rubocop,maxjacobson/rubocop,tdeo/rubocop,bbatsov/rubocop,jmks/rubocop,tdeo/rubocop