`e18e.configs is possibly undefined` when in type-checked eslint config files

[serhalp]

eslint.config.js:48:3 - error ts(18048): 'e18e.configs' is possibly 'undefined'.
  48   e18e.configs.recommended,

The default export is typed as ESLint.Plugin, which means configs is Record<string, ...> | undefined. This forces users who use TypeScript in their eslint configs to work around the "possibly-undefined" e18e.configs property that is actually always an object:

From what I can tell, other eslint plugins avoid this by exporting more specific types for their configs property. Internally I noticed this also manifests as a ! non-null assertion in src/main.ts.

(PR incoming)