AniwatchPlus/tsconfig.json

{
    "compilerOptions": {
      // You have to explicitly set @types to get DefinitelyTyped type definitions
      "typeRoots": ["node_modules/@types", "node_modules/web-ext-types"],
      // Default would be DOM,ES6,DOM.Iterable,ScriptHost (see https://www.typescriptlang.org/docs/handbook/compiler-options.html). However the ES 2020 is required for string.prototype.matchAll (see https://stackoverflow.com/a/57298833).
      "lib": ["ES2020", "DOM", "DOM.Iterable", "ScriptHost"]
    }
  }