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with iemgut's in mind, i would go for [canvaserror] (or, for a more general case: [canvasconsole]).
For beginners, "canvas" is not a common concept as it currently is not explained anywhere as a "patch window" or similar. Hence the name might be difficult to relate to the object's function.
I would call it [patcherror] and explain that it is per canvas in the help-patch, possibly giving it a flag to report all errors. Or [pdebug], or ...
[...]
while thinking about the exception analogy, it might be interesting to be able to re-throw an error message: if you don't want to hande the error in your canvas, you can just pass it on to the parent canvas by sending it to an [error] object.
the same could apply to [print], which can be considered just as a "low-priority error".
Possibly just use print. Can one prefix a print color somehow btw?
best, P