If I'm correct about the reason for this, this should happen with anything Baritone can walk through. Other blocks will be ignored when next to or outside the world border.

Firstly, for canWalkThrough blocks just walking into them won't do the trick. Path execution will walk into them and that's it (honestly I was surprised mining them works anyway). However, there's a second mechanism by which MineProcess can break blocks:
If a target block is in the same xz column as the player and at or above foot height and breaking it won't trigger falling blocks or risk unblocking liquids, then MineProcess will break it.

The check for falling blocks/liquids happens in MovementHelper.avoidBreaking, which also returns true right next to the world border. Normally that's not a problem since MovementHelper.getMiningDurationTicks reports any such block as being unbreakable and MineProcess will completely ignore inbreakable blocks.
However, if a block is canWalkThrough there is no reason for movements to break it, so getMiningDurationTicks shortcuts and returns 0, making MineProcess include it in the pathfinder goal even though it won't be able to break the block.

(I'll hopefully have a fix tomorrow; should be as simple as explicitly checking avoidBreaking)

If I'm correct about the reason for this, this should happen with anything Baritone can walk through. Other blocks will be ignored when next to or outside the world border.

Firstly, for canWalkThrough blocks just walking into them won't do the trick. Path execution will walk into them and that's it (honestly I was surprised mining them works anyway). However, there's a second mechanism by which MineProcess can break blocks: If a target block is in the same xz column as the player and at or above foot height and breaking it won't trigger falling blocks or risk unblocking liquids, then MineProcess will break it.

The check for falling blocks/liquids happens in MovementHelper.avoidBreaking, which also returns true right next to the world border. Normally that's not a problem since MovementHelper.getMiningDurationTicks reports any such block as being unbreakable and MineProcess will completely ignore inbreakable blocks. However, if a block is canWalkThrough there is no reason for movements to break it, so getMiningDurationTicks shortcuts and returns 0, making MineProcess include it in the pathfinder goal even though it won't be able to break the block.

(I'll hopefully have a fix tomorrow; should be as simple as explicitly checking avoidBreaking)

Ohh I see that makes so much sense. There's actually another bug that might be related to this, when when I instruct baritone to break sugar cane. Ot walka into the cane, and looks at the bottom block without breaking it. Probably because theres other sugar cane in the way.