chore(cli): add error log when pages empty

packages/webpack-uni-pages-loader/lib/index-new.js

@@ -62,6 +62,11 @@ module.exports = function (content, map) {
     }
   })
 
+  if (!pagesJson.pages || pagesJson.pages.length === 0) {
+    console.error('pages.json中的pages不能为空')
+    process.exit(0)
+  }
+
   if (global.uniPlugin.defaultTheme) {
     pagesJson = parseTheme(pagesJson)
     this.addDependency(path.resolve(process.env.UNI_INPUT_DIR, 'theme.json'))
@@ -144,4 +149,4 @@ module.exports = function (content, map) {
   }
 
   this.callback(null, '', map)
-}
+}