Incorrect proxy -covertdtls-fingerprint usage causes silent termination

I was trying to follow the instructions at #40530 (closed) to run the proxy with -covertdtls-config randomizemimic. But I accidentally used the wrong option and wrote -covertdtls-fingerprint randomizemimic. When I did that, the program exited after emitting one log line, and no error message.

snowflake/proxy$ ./proxy -covertdtls-fingerprint randomizemimic
2026/04/07 17:02:25 Proxy starting
snowflake/proxy$ echo $?
1

Probably -covertdtls-fingerprint should emit some helpful error message when misused.