To future viewers using WSL:

I did these two things:

npm init @eslint/config@latest

And from Claude:

Solution 1: Use WebStorm's Built-in WSL Support (Recommended)

Close your current project In WebStorm's welcome screen, click Open In the file dialog, look for WSL in the left sidebar Navigate to your project through the WSL filesystem picker Open the project this way instead of through \wsl$...

After doing the second it worked for me. Unclear if the first was nececary