fix(client): make layouts client config optional (close #1494)

Author: meteorlxy

packages/client/src/resolvers.ts

@@ -32,8 +32,8 @@ export const resolvers = reactive({
         ...prev,
         ...item.layouts,
       }),
-      {} as Layouts,
-    ),
+      {},
+    ) as Layouts,
 
   /**
    * Merge the head config in frontmatter and site locale

packages/client/src/types/clientConfig.ts

@@ -24,7 +24,7 @@ export interface ClientConfig {
   /**
    * Layout components
    */
-  layouts?: Layouts
+  layouts?: Partial<Layouts>
 
   /**
    * Components to be placed directly into the root node of vue app