Ignore session id if empty

src/packages/collaboration/lib/collaboration.coffee

@@ -23,6 +23,7 @@ module.exports =
 
       rootView.command 'collaboration:join-session', ->
         new JoinPromptView (id) ->
+          return unless id
           windowSettings =
             bootstrapScript: require.resolve('collaboration/lib/bootstrap')
             resourcePath: window.resourcePath

src/packages/collaboration/lib/join-prompt-view.coffee

@@ -30,7 +30,7 @@ class JoinPromptView extends View
     @miniEditor.setText('')
 
   confirm: ->
-    @confirmed(@miniEditor.getText())
+    @confirmed(@miniEditor.getText().trim())
     @remove()
 
   attach: ->