[widgets][plottereditor] Make resistant to "empty" JSON

Empty as in "{}"

beat/editor/widgets/plottereditor.py

@@ -210,15 +210,12 @@ class PlotterEditor(AbstractAssetEditor):
 
         self.language = json_object.get("language", "")
 
-        selected_dataformat = json_object.get("dataformat", {})
+        selected_dataformat = json_object.get("dataformat", "")
         index = self.dataformat_combobox.findText(
             selected_dataformat, Qt.MatchFixedString
         )
 
-        if index >= 0:
-            self.dataformat_combobox.setCurrentIndex(index)
-        else:
-            raise RuntimeError("Invalid default value")
+        self.dataformat_combobox.setCurrentIndex(index)
 
         self.libraries_widget.set_available_libraries(self.library_model.stringList())
         self.libraries_widget.set_used_libraries(json_object.get("uses", {}))