【报Bug】升级2.6.3后原先写的非V3项目报错

详细问题描述

• 编译过程报错

Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):  
10:45:40.094 ModuleBuildError: Module build failed (from ./node_modules/postcss-loader/src/index.js):  
10:45:40.094 TypeError: config(...).search is not a function  
10:45:40.094     at rc (C:\software\HBuilderX\plugins\uniapp-cli\node_modules\postcss-load-config\src\index.js:88:6)  
10:45:40.110     at Promise.resolve.then (C:\software\HBuilderX\plugins\uniapp-cli\node_modules\postcss-loader\src\index.js:78:12)  
10:45:40.110     at <anonymous>  
10:45:40.110     at process._tickCallback (internal/process/next_tick.js:188:7)  
10:45:40.110     at runLoaders (C:\software\HBuilderX\plugins\uniapp-cli\node_modules\webpack\lib\NormalModule.js:301:20)  
10:45:40.125     at C:\software\HBuilderX\plugins\uniapp-cli\node_modules\loader-runner\lib\LoaderRunner.js:367:11  
10:45:40.125     at C:\software\HBuilderX\plugins\uniapp-cli\node_modules\loader-runner\lib\LoaderRunner.js:233:18  
10:45:40.125     at context.callback (C:\software\HBuilderX\plugins\uniapp-cli\node_modules\loader-runner\lib\LoaderRunner.js:111:13)  
10:45:40.125     at Promise.resolve.then.then.catch (C:\software\HBuilderX\plugins\uniapp-cli\node_modules\postcss-loader\src\index.js:208:9)  
10:45:40.125     at <anonymous>  
10:45:40.125     at process._tickCallback (internal/process/next_tick.js:188:7)  
10:45:40.125  ERROR  Build failed with errors.