[analyzer] No error in case of ?. in a constant expression

[sgrekhov]

With the recent change the following code produces and error in CFE but no error in the analyzer.

const String? c1 = null;
const int? c2 = c1 == null ? null : c1?.length;  // Error: Null-aware property access can't be used in a constant expression.

main() {
  print(c2);
}

@eernstg please confirm that there should be an analyzer error as well.

Dart SDK version: 3.9.0-edge.cddee72854b2c735148751f08eb0cc51d05854c9 (main) (Mon May 5 01:50:25 2025 -0700) on "linux_x64"

[eernstg]

Yes, "this is not a constant expression" is an error for any static analysis, analyzer or CFE, when a constant expression is required.