fix: format unknown type (#275)

Author: stipsan

src/types.ts

@@ -279,7 +279,12 @@ export interface PortableTextMarkComponentProps<M extends TypedObject = Arbitrar
  * Any node type that we can't identify - eg it has an `_type`,
  * but we don't know anything about its other properties
  */
-export type UnknownNodeType = {[key: string]: unknown; _type: string} | TypedObject
+export type UnknownNodeType =
+  | {
+      _type: string;
+      [key: string]: unknown;
+    }
+  | TypedObject;
 
 /**
  * Function that renders any node that might appear in a portable text array or block,