more helpful error messages from DebugLint

lib/coderay/encoders/debug_lint.rb

@@ -35,7 +35,7 @@ def begin_group kind
     end
 
     def end_group kind
-      raise IncorrectTokenGroupNesting, "We are inside #{@opened.inspect}, not #{kind}" if @opened.pop != kind
+      raise IncorrectTokenGroupNesting, "We are inside #{@opened.inspect}, not #{kind} (end_group)" if @opened.pop != kind
       super
     end
 
@@ -45,7 +45,7 @@ def begin_line kind
     end
 
     def end_line kind
-      raise IncorrectTokenGroupNesting, "We are inside #{@opened.inspect}, not #{kind}" if @opened.pop != kind
+      raise IncorrectTokenGroupNesting, "We are inside #{@opened.inspect}, not #{kind} (end_line)" if @opened.pop != kind
       super
     end