The build is failing, and I've figured out why.

[sakots]

Under Ubuntu 21.04, the build failed, and I am trying to figure out why it fails, with error messages.

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: 'node-png@0.4.3',
npm WARN EBADENGINE   required: { node: '0.8.x' },
npm WARN EBADENGINE   current: { node: 'v14.17.0', npm: '7.13.0' }
npm WARN EBADENGINE }
npm WARN deprecated urix@0.1.0: Please see https://github.com/lydell/urix#deprecated
npm WARN deprecated resolve-url@0.2.1: https://github.com/lydell/resolve-url#deprecated
npm WARN deprecated mkdirp@0.5.4: Legacy versions of mkdirp are no longer supported. Please update to mkdirp 1.x. (Note that the API surface has changed to use Promises in 1.x.)
npm WARN deprecated request@2.88.2: request has been deprecated, see https://github.com/request/request/issues/3142
npm WARN deprecated phantomjs-prebuilt@2.1.16: this package is now deprecated
npm WARN deprecated har-validator@5.1.5: this library is no longer supported
npm WARN deprecated node-pre-gyp@0.15.0: Please upgrade to @mapbox/node-pre-gyp: the non-scoped node-pre-gyp package is deprecated and only the @mapbox scoped package will recieve updates in the future
npm WARN deprecated popper.js@1.16.1: You can find the new Popper v2 at @popperjs/core, this package is dedicated to the legacy v1

I think the environment to develop may be too old, is there any reason for that?

[sakots]

I'll also post the results of the npm audit.

minimist  <0.2.1 || >=1.0.0 <1.2.3
Prototype Pollution - https://npmjs.com/advisories/1179
No fix available
node_modules/optimist/node_modules/minimist
  optimist  >=0.6.0
  Depends on vulnerable versions of minimist
  node_modules/optimist
    icomoon-build  *
    Depends on vulnerable versions of optimist
    node_modules/icomoon-build

3 low severity vulnerabilities

Some issues need review, and may require choosing
a different dependency.

[thenickdude]

None of those are errors, they are only warnings. This is a successful install.

You need to run "make" if you want to build the package too.

[sakots]

I've solved the riddle! "make" was also executed automatically. I apologize for the inconvenience.