fix(mp): 修复language属性为undefined时接口报错的Bug

src/platforms/mp-weixin/helpers/enhance-system-info.js

@@ -79,7 +79,7 @@ export function populateParameters (result) {
   if (__PLATFORM__ === 'mp-alipay') { _SDKVersion = my.SDKVersion }
 
   // hostLanguage
-  const hostLanguage = language.replace(/_/g, '-')
+  const hostLanguage = (language || '').replace(/_/g, '-')
 
   // wx.getAccountInfoSync
 

src/platforms/mp-weixin/helpers/get-app-base-info.js

@@ -7,7 +7,7 @@ export default {
 
     const _hostName = getHostName(result)
 
-    const hostLanguage = language.replace('_', '-')
+    const hostLanguage = (language || '').replace('_', '-')
 
     result = sortObject(Object.assign(result, {
       appId: process.env.UNI_APP_ID,