[extension-types] Analyzer sees nullable extension type as non nullable.

[Quijx]

The analyzer shows no errors for the following code:

void main() {
  bar(null);
}

void bar(Foo? foo) {
  print(foo.i);
}

extension type Foo(int i) {}

However when running it, the following error is correctly shown by the CFE:

bin/dart_bug_nullable_extension_type.dart:6:13: Error: Property 'i' cannot be accessed on 'Foo?' because it is potentially null.
Try accessing using ?. instead.
  print(foo.i);
            ^

The expectation would be that the analyzer disallows foo.i in the print aswell.

This happens on Dart 3.2.3 as well as on the current master channel in dartpad.dev (3.3.0-279.0.dev)

[Quijx]

This bug is still present in Dart 3.2.0 stable. Also this issue needs the feature-extension-types tag i think.

[matanlurey]

I'd encourage thinking about this as P1, as the extension types feature seems incomplete without it.

(As mentioned elsewhere, yes the compiler will catch this)

[eernstg]

I don't see the error in the analyzer today (the DartPad main channel analyzer does report the error).

[parlough]

Yep. I believe https://github.com/dart-lang/sdk/commit/421ffd331a1262e0bd23ea69298c3cd52718c04f fixed this which is now in the latest dev and main channel releases :D