When intentionally generating an error in AppleScript you can supply the error message and number (and probably the other parameters, if you care about them). If this error is not trapped by a try handler, it is passed back to the caller.
What I discovered today is this: if you generate an error and give it error number 0, Script Debugger does not report the error in its standard error sheet. (AppleScript Editor does report the error.)
I’m not sure if this is an intentional bit of niceness — it gives you a way of stopping the script without being bothered by a dialog — or a mistake based on the fact that, in Cocoa, et. al. “error 0” means noErr.
In the Mountain Lion Server User configuration panel, you can set a disk quota for each user. Be warned that setting a “really large” quota (500GB in my test) can cause quota errors. I don’t know whether the value is setting a high bit and ‘going negative’ or overflowing some variable so it wraps around to a small value, but there it is.
Here is Software Update Controller (xhost7) for the other machines on my LAN. It won’t work outside my local network, so don’t bother trying.
Time Machine has been skipping some folders, and every simple trick I tried failed to make it back them up. Finally, I dug deep and found the problem: the OS X Extended Attributes for those folders contained this attribute: com.apple.metadata:com_apple_backup_excludeItem
The “how to remove this” instructions came from stackoverflow.com.