Class optional member should not be initialized to undefined #25412
Description
What version of Bun is running?
1.3.4+5eb2145b3
What platform is your computer?
Darwin 25.1.0 arm64 arm
What steps can reproduce the bug?
This TS snippet creates a class with optional member, and check if the member exists with in.
class X { val?: number }
console.log("val" in new X())
What is the expected behavior?
false is printed to match TS behaviour.
What do you see instead?
true is printed.
Additional information
No response