What and why?

Fix Live Debugger instrumentation for arrows that execute before super() completes in derived class constructors. The transform previously injected probe calls that accessed this, which can crash valid derived-constructor code while super() arguments are still being evaluated.

Before instrumentation, this pattern is valid:

class B extends A {
  constructor(items) {
    super(items.map((x) => x * 2));
  }
}

Before this fix, probing the arrow could inject code that accessed constructor this before super() returned:

super(items.map((x) => {
  if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
  const $dd_rv0 = x * 2;
  if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0());
  return $dd_rv0;
}));

After this fix, affected arrows use a constructor-scoped $dd_t alias that is assigned from super():

constructor(items) {
  let $dd_t;
  ($dd_t = super(items.map((x) => {
    if ($dd_p0) $dd_entry($dd_p0, $dd_t, $dd_e0());
    const $dd_rv0 = x * 2;
    if ($dd_p0) $dd_return($dd_p0, $dd_rv0, $dd_t, $dd_e0());
    return $dd_rv0;
  })));
}

How?

The transform now detects arrows whose lexical this comes from a derived constructor, emits one constructor-scoped $dd_t alias, and assigns it from wrapped super() calls. Affected arrows pass $dd_t to $dd_entry, $dd_return, and $dd_throw; arrows outside derived constructors and non-arrow function expressions continue to use their normal this.

Added regression coverage for the reported super(items.map((x) => x * 2)) pattern, a guard for non-arrow function expressions, and an exact-output smoke test for the generated $dd_t shape.

Verified with:

• yarn test:unit packages/plugins/live-debugger/src/transform/index.test.ts
• yarn lint packages/plugins/live-debugger/src/transform/index.ts packages/plugins/live-debugger/src/transform/index.test.ts
• yarn cli typecheck-workspaces --files packages/plugins/live-debugger/src/transform/index.ts --files packages/plugins/live-debugger/src/transform/index.test.ts