feat: semantic layer extension (#37815)

superset/commands/explore/get.py

@@ -126,7 +126,11 @@ class GetExploreCommand(BaseCommand, ABC):
             security_manager.raise_for_access(datasource=datasource)
 
         viz_type = form_data.get("viz_type")
-        if not viz_type and datasource and datasource.default_endpoint:
+        if (
+            not viz_type
+            and datasource
+            and getattr(datasource, "default_endpoint", None)
+        ):
             raise WrongEndpointError(redirect=datasource.default_endpoint)
 
         form_data["datasource"] = (