I am using a project generated by @nrwl/nx and they are working with eslint config file extension a lot. Sub projects have new .eslintrc files which extend base .eslintrc files. Also I use the automatic eslint config of webstorm.
One .eslintrc file in a subfolder is extending a base .eslintrc file which is in the root of the project. That root .eslintrc itself has a parserOptions object and requires a tsconfig.base.json file with a relative path. The bundled automatic eslint resolver from webstorm cannot resolve the tsconfig, as the path is resolved from the subfolder instead of the root folder which it should be. Running eslint from the cli does work fine, so I don't think it's a config error, rather than an error in the file resolution.
The screenshot shows, how ESLint tries to resolve the .../foobar/apps/fooapp/tsconfig.base.json instead of the .../foobar/tsconfig.base.json
The root .eslintrc file requires the base file with ./tsconfig.base.json. My guess is, that the nearest .eslintrc file is picked up by webstorm, which is in .../foobar/apps/fooapp/.eslintrc and sets that as new working directory, which is wrong in that case.
Thanks in advance.