The error came from an installed script (the reasons for the error are explained by SmokingCookie).
However, that source you showed seems to be a (older?) buggy version of
WLNameEditor as Mnjul said. The version listed in the scripting database does not have that error.
All installed scripts should appear in the scripting preferences:
Plus! > Preferences & Options > General > Scripts
If there is a script running, but it isn't listed in that list, then you have some serious (other) problems. I have never heared of this happening before though, nor have I heared of cache problems like that.
PS: Users do not need to be logged in into Messenger for scripts to run. Scripts start running the moment you start Messenger (and Plus! is loaded). A user logging in is just another event which scripts can interact with. This also means that scripts will not stop running when the user signs out.
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What do you mean with "precache"???
Can you explain in great detail how you cleared this "precache"?
Messenger Plus! nor Messenger doesn't use any cache (that is: for scripting or stuff like that). Your Temporary Internet Files or any other form of cache from other programs should not have any influence at all on Plus! or Messenger. But since you had that error, it sure wasn't a "clean install" though.
Anyways, if you couldn't edit the script then how did you manage to show the source of it? Where did that came from? Can you explain in detail how you got that source (from what location)?
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