Move the aborted fiber check in runFiber to execute before the "already called" check, ensuring a clear error message for aborted fibers. In runtimeError, replace the single caller unhook with a loop that walks the fiber chain, preserving the callerIsTrying flag and only unhooking fibers until a try-catch boundary is found, enabling proper error propagation through nested fiber calls. Add test cases for one and two levels of nested fiber try calls.