Warning if no installed packages yet

[geraldo]

This could be related to point 3 of #20 as this warning appears in case that there are no installed packages yet:

2024-10-14T09:07:35 WARNING warning:/usr/lib/python3.10/subprocess.py:1072: ResourceWarning: subprocess 58526 is still running
_warn("subprocess %s is still running" % self.pid,
traceback: File "[...]profiles/default/python/plugins/a00_qpip/plugin.py", line 283, in show_folder
subprocess.Popen(["xdg-open", self.prefix_path])
File "/usr/lib/python3.10/subprocess.py", line 1072, in del
_warn("subprocess %s is still running" % self.pid,