pngquant pre-build test failed

在安装layaair2-cmd的过程中，报了一个错。

pngquant pre-build test failed.

Error:pngquant failed to build,make sure that libpng-dev is installed.

不得不说，Error信息让我走了弯路，找了好久的libpng-dev这个库。

折腾了半天都不行，找到了pngquant库的github主页，在readme底部发现了一句话。

Make sure you have node.js and npm installed, and that the pngquant binary is in your PATH,

瞬间搞定了这个问题，解决方案如下：

1、前往https://pngquant.org/下载pngquant库

2、在计算机环境变量中添加 pngquant库目录

3、再次安装npm pngquant即可。

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总的来说，如果上面的报错信息写成

Error:pngquant failed to build,Make sure you have node.js and npm installed, and that the pngquant binary is in your PATH。

就不会有这个坑了。