I tested it and I take it back. I think there may be a bug, but not one you're referring to. Allow me to explain.
My test:
What it's doing is picking a point near you and saying, "Drop the canoe there!" But then it realizes "Oh ****, there's something in the way." Now, what it does next is the issue - it says, "Well, if I can't put it there, let's check another few tiles away from the player." And it loops that, continuing to searching for an open spot until it can drop the canoe. Also, if there is a bug, it's here, because I think it increases its range exponentially the further you get from the character in order to drop the canoe (again, this would be a resource-saving technique to limit the amount of spots it would check as clearly you are clearly in a very object-dense area) (or it uses the object's bounding box that's in the way) which means that the more cluttered your area OR the further the empty space is from you OR the bigger the object is that it tried to place it on (not sure about this precisely), the further it will be, which is why sometimes it's very very deep into walls. If I were to tell the code, "But make it so that it can't drop on black void tiles!" it would probably crash the server as the game continue to launch the canoe into oblivion, trying to find a place to put it.
The issue I have is coming up with an alternative. Because what I don't believe is happening right now, which we don't want to do, is checking ALL available spaces. That's a huge waste of resources. "Check every pixel around the character to see if it's empty" is a good way to bog down the server. Also what we don't want to do is have it do what it's currently doing and NOT check other spaces in a direction and just give you a message that says "You can't put that there!" because what will happen is that you'll obviously (to you) have room around you, but since the game isn't checking all the spaces around you and just a single space, it will get quite frustrating.
However, as I'm talking this out to myself, I think there actually might be a solution. It would make it, though, that you cannot be carrying an item when dropping a canoe. What I would have it do is, when you control+left click the canoe to drop it, it would instead put it over your head as though you were "lift" carrying it. You could then place it as you would any carried object. Perhaps that is what needs to happen here. You would at least never see another canoe inside a wall - probably.