Setting useFlatConfig to true breaks ESLint integration for projects that use the older config style

[NathanKleekamp]

If you set "eslint.experimental.useFlatConfig": true in the coc-settings.json file, it fails silently on projects that use ESLint's older config style. You get no warning that ESLint is essentially disabled.

When I switch projects, I have to manually update the coc-settings.json file. This doesn't happen in VSCode, which seems to determine per project the correct type of ESLint config to use.

[mcmire]

Can confirm. Was pulling my hair out trying to figure out why ESLint wasn't running in my project and remembered that I'd set this setting.