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I have an npm project which needs to build on both Mac and Windows build servers. (This is for an Ionic mobile app, but I don't think that is relevant to my issue.) One of our dependencies has a dependency on fsevents, which is skipped by npm install on Windows machines. However, if I run npm list --depth=0, it is returning errors about missing dependencies of optional dependencies.

Minimal package.json to reproduce:

 "dependencies": 
 "@ionic/app-scripts": "^3.2.0"
 

Then I run npm install:

C:tempnodetest>npm install
...
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.7 (node_modulesfsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.7: wanted "os":"darwin","arch":"any" (current: "os":"win32","arch":"x64")

Notice that it skips fsevents because it does not support Windows OS.

Now I run npm list:

C:tempnodetest>npm list --depth=0
C:tempnodetest
`-- @ionic/app-scripts@3.2.3

npm ERR! missing: mkdirp@0.5.1, required by node-pre-gyp@0.10.3
npm ERR! missing: minimist@0.0.8, required by mkdirp@0.5.1
npm ERR! missing: minimatch@3.0.4, required by ignore-walk@3.0.1
... (many other errors like this)

The errors are all due to dependencies of the uninstalled optional dependency. Is there any way to suppress these errors? I'm not seeing anything in the npm list documentation.

My ultimate goal is to verify that all dependencies are installed, and fail the build otherwise. I'm currently using npm list to do that. Is there a better way to do this? We don't want to run npm install or npm update on every build, because we got many surprise bugs in the past when we did that.

I've also tried npm list --depth=0 --no-optional (based on this question), but it doesn't look like --no-optional command is relevant to npm list.