debugger: remove undefined parameter

The data parameter of unpackError() is typically undefined.

PR-URL: https://github.com/nodejs/node/pull/39570
Refs: https://github.com/nodejs/node-inspect/issues/101


Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>