test: check type for Worker filename argument

Add test to check type for first argument of Worker to increase
coverage.

PR-URL: https://github.com/nodejs/node/pull/21620


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>