What does the "invalid"-tag mean in `npm list`?

Question

Given the following snippet of npm list output:

...
├─┬ [email protected] invalid
│ ├─┬ [email protected]
│ │ └── [email protected]
│ ├── [email protected]
│ ├── [email protected]
│ └── [email protected]
...

I asked myself: "What does invalid mean?" However, all I could find in the documentation about it is the following:

[npm list] will print out extraneous, missing, and invalid packages. --source

...So now I'm asking you.

Answer 1

The invalid tag appears when the version of the installed dependency does not match the version required in package.json. Often this will occur when a dependency is required in dependencies as well as an incompatible version in devDependencies.