fix pane function calling

Author: aminya

lib/ui/layout.js

@@ -30,7 +30,7 @@ export function closePromises () {
   const panes = specifiedPanes()
 
   const promises = panes.map(pane => {
-    return pane().close()
+    return pane.close()
   })
 
   return promises
@@ -75,10 +75,10 @@ function openPanesHelper (panes) {
   }
 
   const pane = panes.shift()
-  pane().open().catch((err) => {
+  pane.open().catch((err) => {
     // @FIXME: This is a temporal remedy for https://github.com/JunoLab/atom-julia-client/pull/561#issuecomment-500150318
     console.error(err)
-    pane().open()
+    pane.open()
   }).finally(() => {
     // Re-focus the previously focused pane (i.e. the bundled pane by `bundlePanes`) after each opening
     // This prevents opening multiple panes with the same splitting rule in a same location from