Incorrect error is thrown when "/" is used in the 'unity install' argument

Steps to reproduce:

1. Open Terminal
2. Run "unity install /"
3. Observe the Terminal and the logs

Actual result: "NETWORK_UNREACHABLE" code error is thrown

Expected result: Another code error is thrown (like "INVALID_VERSION")

Reproducible with versions: 1.0.0-beta.6

Tested on (OS): Windows 11 Pro (25H2)