Dogfood ty on py-fuzzer in CI (#20946)

python/py-fuzzer/fuzz.py

@@ -139,7 +139,7 @@ class FuzzResult:
                 case Executable.TY:
                     panic_message = f"The following code triggers a {new}ty panic:"
                 case _ as unreachable:
-                    assert_never(unreachable)
+                    assert_never(unreachable)  # ty: ignore[type-assertion-failure]
 
             print(colored(panic_message, "red"))
             print()

python/py-fuzzer/pyproject.toml

@@ -32,6 +32,10 @@ warn_unreachable = true
 local_partial_types = true
 enable_error_code = "ignore-without-code,redundant-expr,truthy-bool"
 
+[tool.ty.rules]
+possibly-unresolved-reference = "error"
+unused-ignore-comment = "error"
+
 [tool.ruff]
 fix = true
 preview = true