optional call `obj.fn?.(...)` throws when fn is undefined (should short-circuit to undefined)

[proggeramlug]

Surfaced by the new feature-matrix probe test-files/test_feat_optional_chaining.ts (added under #801).

Repro

interface User { greet?: (who: string) => string }
const sparse: User = { id: 2 } as User;
console.log("sparse.greet?.('bob'):", sparse.greet?.("bob"));

Expected (Node)

sparse.greet?.('bob'): undefined

Actual (Perry v0.5.914)

TypeError: greet is not a function
    at <anonymous>

The optional-call form obj.fn?.(...) must short-circuit to undefined when obj.fn is null/undefined — it must not invoke the call at all. Perry is currently evaluating the call site regardless of the ?. short-circuit.

Property-access optional chain works

The plain ?.email/?.phone?.work forms in the same test pass — only the optional-CALL form is broken.

Impact

This blocks ~all real-world TS code that uses optional method invocation (event-handler patterns, optional callbacks).

Part of #793 (axis 1 — TypeScript language). Surfaced by the #801 feature matrix.