I only have back to Cache 2018, not 2017, but can you try:

set myproc = ##class(%SYS.ProcessQuery).%OpenId($J)
if myproc.ClientExecutableName = "CSTUDIO.EXE"{
    //You are in Cache Studio
}
else{
    //You are not in Cache Studio
}

I'm not totally clear on what you're trying to do, but I have a feeling you might want to replace "quit" with "return status". Inside a catch block, a quit command will quit just the catch block and code execution will continue after it. Replacing that with return status would make the code execution stop right there, returning the error.

Here's my small but useful contribution:

Add an "Add Server to VS Code" Option to System Tray Icon