Unity has warnings after installing this package

[Kotsuha]

Thank you for this package.

After installing this package, everything works fine, except that these warnings show up everytime I restart Unity.

A meta data file (.meta) exists but its asset 'Packages/com.wooshii.foldericons/package-lock.json' can't be found. When moving or deleting files outside of Unity, please ensure that the corresponding .meta file is moved or deleted along with it.

Couldn't delete Packages/com.wooshii.foldericons/package-lock.json.meta because it's in an immutable folder.

I installed this package by going to the Package Manager window > Add package from git URL... > https://github.com/WooshiiDev/Unity-Folder-Icons.git

Unity version 2020.3.30f1

[Kotsuha]

The warnings are gone after I delete 'Library\PackageCache\com.wooshii.foldericons@4511fb0\package-lock.json.meta' manually.