Implement ProtocolTemplateEditor

Summary

This merge request implements the editor for the ProtocolTemplate asset

Relevant issue(s) fixed

Fixes #210 (closed)

beat/editor/widgets/protocoltemplateeditor.py

@@ -270,10 +270,13 @@ class ProtocolTemplateEditor(AbstractAssetEditor):
             set_widget.dataChanged.connect(self.dataChanged)
             set_widget.deletionRequested.connect(self.__on_remove_requested)
 
-        QTimer.singleShot(
-            100,
-            lambda: self.scroll_area.ensureWidgetVisible(self.set_widgets[-1], 10, 10),
-        )
+        if self.set_widgets:
+            QTimer.singleShot(
+                100,
+                lambda: self.scroll_area.ensureWidgetVisible(
+                    self.set_widgets[-1], 10, 10
+                ),
+            )
 
     def _load_json(self, json_object):
         """Load the json object passed as parameter"""