A throw in a try that declares a class-typed let is not caught (crash in every model) #457

A throw inside a try block that declares a class-typed let is not caught: the program crashes instead of running the catch.

class Node { v = 0; }

function tryIt(s: Node) {
    try {
        let t = s;
        print("in try", t.v);
        throw 1;
    } catch {
        print("caught", s.v);
    }
}

function main() {
    const a = new Node();
    tryIt(a);
    print("after", a.v);
}

Expected: in try 0, caught 0, after 0.

Actual, tslang --emit=jit --no-default-lib, main 8b9d631: in try 0, then a crash.

• gc and none: exception 0x80000003, exit 3. The same happens with the default library.
• rc: 0xC0000005, exit 139.
• AOT: 0xC0000409.

These versions of the try body are caught correctly (caught 0, after 0):

• const t = s; instead of let t = s;;
• a number local, let n = 5;;
• no local at all.

let t = new Node(); crashes the same way. So the trigger is a let of a class type declared in the try, followed by a throw.

This is probably the same root cause as #456, where a class-typed let in try has an initializer that throws. Here the initializer succeeds and a later statement throws.

Found by the final review of Shared<T> (own phase 8).

🤖 Generated with Claude Code