Don't explode on meta-/ if there isn't a valid comment regex

spec/app/edit-session-spec.coffee

@@ -1,6 +1,7 @@
 Project = require 'project'
 Buffer = require 'buffer'
 EditSession = require 'edit-session'
+TextMateBundle = require 'text-mate-bundle'
 
 describe "EditSession", ->
   [buffer, editSession, lineLengths] = []
@@ -1347,6 +1348,12 @@ describe "EditSession", ->
         editSession.toggleLineCommentsInSelection()
         expect(editSession.getSelection().isEmpty()).toBeTruthy()
 
+      it "does not explode if the current language mode has no comment regex", ->
+        spyOn(TextMateBundle, 'lineCommentStringForScope').andReturn(null)
+        editSession.setSelectedBufferRange([[4, 5], [4, 5]])
+        editSession.toggleLineCommentsInSelection()
+        expect(buffer.lineForRow(4)).toBe "    while(items.length > 0) {"
+
     describe ".undo() and .redo()", ->
       it "undoes/redoes the last change", ->
         editSession.insertText("foo")

src/app/language-mode.coffee

@@ -47,7 +47,8 @@ class LanguageMode
   toggleLineCommentsInRange: (range) ->
     range = Range.fromObject(range)
     scopes = @tokenizedBuffer.scopesForPosition(range.start)
-    commentString = TextMateBundle.lineCommentStringForScope(scopes[0])
+    return unless commentString = TextMateBundle.lineCommentStringForScope(scopes[0])
+
     commentRegex = new OnigRegExp("^\s*" + _.escapeRegExp(commentString))
 
     shouldUncomment = commentRegex.test(@editSession.lineForBufferRow(range.start.row))