Destroy all pane models when workspace view is removed

src/pane-container.coffee

@@ -83,3 +83,7 @@ class PaneContainer extends Model
 
   itemDestroyed: (item) ->
     @emit 'item-destroyed', item
+
+  # Private: Called by Model superclass when destroyed
+  destroyed: ->
+    pane.destroy() for pane in @getPanes()

src/pane.coffee

@@ -203,7 +203,7 @@ class Pane extends Model
     @destroyItem(item) for item in @getItems() when item isnt @activeItem
 
   destroy: ->
-    super unless @container?.getPanes().length is 1
+    super unless @container?.isAlive() and @container?.getPanes().length is 1
 
   # Private: Called by model superclass.
   destroyed: ->

src/workspace-view.coffee

@@ -238,8 +238,11 @@ class WorkspaceView extends View
     @on('editor:attached', attachedCallback)
     off: => @off('editor:attached', attachedCallback)
 
+  # Private: Called by SpacePen
+  beforeRemove: ->
+    @model.destroy()
+
   # Private: Destroys everything.
   remove: ->
-    @model.destroy()
     editorView.remove() for editorView in @getEditorViews()
     super

src/workspace.coffee

@@ -145,3 +145,7 @@ class Workspace extends Model
   onPaneItemDestroyed: (item) =>
     if uri = item.getUri?()
       @destroyedItemUris.push(uri)
+
+  # Private: Called by Model superclass when destroyed
+  destroyed: ->
+    @paneContainer.destroy()