Generating new adress with empty descriptor gives 0 exit code

[torkelrogstad]

Describe the bug
Calling get_new_address with an empty descriptor prints an error, but exits with 0.

To Reproduce

$ bdk-cli --network signet wallet --descriptor "" get_new_address
$ echo $?
0

Expected behavior
I'd expect a non-0 exit code.

Build environment

• BDK-CLI tag/commit: 0.27.1
• OS+version: macOS
• Rust/Cargo version: cargo 1.74.1 (ecb9851af 2023-10-18)