Fix entityMapping schema definition

Author: mglaman

extension.neon

@@ -28,12 +28,15 @@ parameters:
 parametersSchema:
 	drupal: structure([
 		drupal_root: string()
-		entityMapping: arrayOf(
+		entityMapping: arrayOf(anyOf(
 			structure([
 				class: string()
-				storage: schema(string(), nullable())
+			]),
+			structure([
+				class: string()
+				storage: string()
 			])
-		)
+		))
 	])
 rules:
 	- mglaman\PHPStanDrupal\Rules\Classes\PluginManagerInspectionRule