直接git clone weui小程序的项目，然后wepy build会出错。即使之前你运行npm install。
我是直接报：[WARNING] 找不到编译器：wepy-compiler-less。
解决方案不复杂：先npm install less 再 wepy build，一般就解决了。build的时候会自己安装wepy-compiler-less。
如果象我，还遇到下面的错误
npm WARN eslint-config-standard@7.1.0 requires a peer of eslint-plugin-promise@>=3.3.0 but none is installed. You must install peer dependencies yourself.
npm WARN wepy-compiler-less@1.3.14 requires a peer of less@^3.8.1 but none is installed. You must install peer dependencies yourself.
npm WARN wepy-weui-demo@1.0.0 No repository field.
+ wepy-compiler-less@1.3.14
updated 1 package and audited 7975 packages in 3.378s
found 10 vulnerabilities (7 low, 3 moderate)
这时候就需要根据提示：npm install -g eslint-plugin-promise@>=3.3.0，进行安装（其实上面也有说，是因为less没有安装）
这样的话，其实问题就都好解决