• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

{
  "rules": {
    "no-fallthrough": [2]
  }
}

declare const n: { a: 1; b: 1 | 2 } | { a: 2 };
(() => {
  switch (n.a) {
    case 1: {
      switch (n.b) {
        case 1:
          return 1;
        case 2:
          return 1;
      }
    }
    // ESLint error:
    // Expected a 'break' statement before 'case'.
    case 2: {
      return 2;
    }
  }
})();

Expected Result

No lint error

Actual Result

Lint error (see comment)

Additional Info

I think the TS ESLint plugin needs to provide its own version of no-fallthrough in order to take advantage of type information so we can avoid false positives such as this.

Versions