lt-wg does not fail correctly if wg-quick fails

Sample run

Using config file /tmp/xxxxxxxx.conf
Launched child 4346
Error: Failed to launch wg-quick: ""
"wg-quick: The config file must be a valid interface name, followed by .conf\n"
Your range VPN should be up, keep this program running, press enter to shut down the VPN...

Expected behavior:

Using config file /tmp/xxxxxxxx.conf
Launched child 4346
Error: Failed to launch wg-quick: ""
"wg-quick: The config file must be a valid interface name, followed by .conf\n"
Failed to launch VPN