workaround for buggy lexers

CHANGELOG

@@ -4,6 +4,7 @@ v 7.12.0 (unreleased)
 - Allow to configure location of the `.gitlab_shell_secret` file. (Jakub Jirutka)
 
 v 7.11.0 (unreleased)
+  - Fall back to Plaintext when Syntaxhighlighting doesn't work. Fixes some buggy lexers (Hannes Rosenögger)
   - Fix broken view when viewing history of a file that includes a path that used to be another file (Stan Hu)
   - Don't show duplicate deploy keys
   - Fix commit time being displayed in the wrong timezone in some cases (Hannes Rosenögger)

app/helpers/blob_helper.rb

@@ -9,11 +9,13 @@ module BlobHelper
 
     begin
       lexer = Rugments::Lexer.guess(filename: blob_name, source: blob_content)
-    rescue Rugments::Lexer::AmbiguousGuess
+      result = formatter.format(lexer.lex(blob_content)).html_safe
+    rescue
       lexer = Rugments::Lexers::PlainText
+      result = formatter.format(lexer.lex(blob_content)).html_safe
     end
 
-    formatter.format(lexer.lex(blob_content)).html_safe
+    result
   end
 
   def no_highlight_files