Fix issue with schema generation when datasource is undefined

packages/builder/src/builderStore/dataBinding.js

@@ -536,12 +536,14 @@ export const getSchemaForDatasource = (asset, datasource, options) => {
     }
 
     // Add schema properties if required
+    if (schema) {
       if (addId) {
         schema["_id"] = { type: "string" }
       }
       if (addRev) {
         schema["_rev"] = { type: "string" }
       }
+    }
 
     // Ensure there are "name" properties for all fields and that field schema
     // are objects