前端换成 Bootstrap3 后报错 The Mix manifest does not exist.

教程里的编辑器能插本地图片这里插不了?汗/
laravel报错：
ErrorException (E_ERROR)

The Mix manifest does not exist. (View: E:\laragon\www\larabbs\resources\views\welcome.blade.php)

npm run watch-poll报错：
ERROR in ./resources/sass/app.scss
Module build failed (from ./node_modules/css-loader/index.js):
ModuleBuildError: Module build failed (from ./node_modules/sass-loader/lib/loader.js):

undefined
^
Incompatible units px and rem.
╷
214 │ $input-height-base: ($line-height-computed + ($padding-base-vertical * 2) + 2) !default;
│ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
╵
node_modules\bootstrap-sass\assets\stylesheets\bootstrap_variables.scss 214:35 @import
node_modules\bootstrap-sass\assets\stylesheets_bootstrap.scss 8:9 @import
stdin 5:9 root stylesheet

只复制了一部分，