From 74887c50da1001df27b9ece1d8f10cb611ac4728 Mon Sep 17 00:00:00 2001
From: Shigma <33423008+Shigma@users.noreply.github.com>
Date: Sun, 7 Apr 2019 00:55:49 +0800
Subject: [PATCH] feat($core): assert return type for functional plugin (#1516)

---
 packages/@vuepress/core/lib/node/plugin-api/util.js | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/packages/@vuepress/core/lib/node/plugin-api/util.js b/packages/@vuepress/core/lib/node/plugin-api/util.js
index a0d7be90ed..b3c17a5025 100644
--- a/packages/@vuepress/core/lib/node/plugin-api/util.js
+++ b/packages/@vuepress/core/lib/node/plugin-api/util.js
@@ -43,6 +43,14 @@ exports.flattenPlugin = function (
     // 'Object.create' here is to give each plugin a separate context,
     // but also own the inheritance context.
     config = config(pluginOptions, Object.create(pluginContext), self)
+    const { valid, warnMsg } = assertTypes(config, [Object])
+    if (!valid) {
+      logger.warn(
+        `[${chalk.gray(shortcut)}] `
+        + `Invalid value for plugin: ${warnMsg}`
+      )
+      config = {}
+    }
   }
 
   // respect name in local plugin config