check for available decorators before disposing

Author: JonathanYee

lib/minimap-highlight-selected.coffee

@@ -53,7 +53,7 @@ class MinimapHighlightSelected
     @decorations.push decoration
 
   markersDestroyed: =>
-    @decorations.forEach (decoration) -> decoration.destroy()
+    @decorations?.forEach (decoration) -> decoration.destroy()
     @decorations = []
 
   deactivatePlugin: ->