Don't update highlighted gutter lines unless the editor is alive

src/editor-view.coffee

@@ -217,6 +217,8 @@ class EditorView extends View
       do (name, method) =>
         @command name, (e) => method.call(this, e); false
 
+  isAlive: -> @editor?.isAlive()
+
   # {Delegates to: Editor.getCursor}
   getCursor: -> @editor.getCursor()
 

src/gutter.coffee

@@ -230,6 +230,8 @@ class Gutter extends View
       @highlightedLineNumbers.push(highlightedLineNumber)
 
   highlightLines: ->
+    return unless @getEditorView().isAlive()
+
     if @getEditorView().getSelection().isEmpty()
       row = @getEditorView().getCursorScreenPosition().row
       rowRange = new Range([row, 0], [row, 0])