Command I tried
$ npm i –unsafe-perm

Got following Error;

 ✔ pngquant pre-build test passed successfully
  ✖ Error: pngquant failed to build, make sure that libpng-dev is installed
    at /opt/lampp/htdocs/sp-admin-ms/node_modules/pngquant-bin/node_modules/bin-build/node_modules/execa/index.js:231:11
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async Promise.all (index 0)
npm WARN ajv-keywords@3.4.1 requires a peer of ajv@^6.9.1 but none is installed. You must install peer dependencies yourself.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.9 (node_modules/fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.9: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! pngquant-bin@4.0.0 postinstall: `node lib/install.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the pngquant-bin@4.0.0 postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/ubuntu/.npm/_logs/2020-01-21T07_01_47_306Z-debug.log

Solution

$ apt-get install libpng-dev