This is perhaps a non-issue if you know what you're doing, but (mistakingly) using non-existing functions returns non-expected results. For example, I would expect
to be invalid or do nothing since the function $nonex doesn't exist. But it actually returns "yes" or "no" depending on the presence of %test% or %example%.
I noticed this when I tried the mac functions
$lt(x,y) in windows. I wasn't expecting them to work in windows, but at first they actually seemed to do so. After a while I noticed that they return identical results, which made me realize that they're not implemented in the windows version - they're only behaving as any non-existing function would.
I don't know if this is a bug or some kind of simplification in the program code, but in any case I find it confusing.