[Bug] Schematic builder tries to path to an unexisting block after finishing a layer

`#build` always tries to go to a block location that doesn't exist in the schematic every time it finishes building a layer after about layer 120.

Basically, it tries to do this:


There is definitely nothing wrong with the schematic file because it was trying to do this on several layers already. On the previous occurrences, it did fine when I did `#stop` and then redo `#build` for every layer, but doing that for every layer is just too inconvenient.

Also, it worked properly when I separated the schematic into two separate ones by y level and build the upper half.

## Some information
Operating system: Windows
Java version: 1.8
Minecraft version: 1.14.4
Baritone version: 1.4.4

## Exception, error or logs
```
[19:38:55] [main/INFO]: [CHAT] [Baritone] Favoring size: 5348
[19:38:55] [main/INFO]: [CHAT] [Baritone] Starting to search for path from BetterBlockPos{x=416,y=188,z=832} to JankyComposite Primary: GoalComposite[GoalBlock{x=416,y=188,z=839}, GoalBlock{x=416,y=188,z=838}] Fallback: GoalComposite[]
[19:38:55] [main/INFO]: [CHAT] [Baritone] Took 113ms, 86438 movements considered
[19:38:55] [main/INFO]: [CHAT] [Baritone] Path ends within loaded chunks
[19:38:55] [main/INFO]: [CHAT] [Baritone] Finished finding a path from BetterBlockPos{x=416,y=188,z=832} to JankyComposite Primary: GoalComposite[GoalBlock{x=416,y=188,z=839}, GoalBlock{x=416,y=188,z=838}] Fallback: GoalComposite[]. 3930 nodes considered
[19:38:56] [main/INFO]: [CHAT] [Baritone] bb pls get me some blocks. dirt, netherrack, cobble
[19:38:56] [main/INFO]: [CHAT] [Baritone] Movement returns status UNREACHABLE
[19:38:56] [main/INFO]: [CHAT] [Baritone] Favoring size: 5348
[19:38:56] [main/INFO]: [CHAT] [Baritone] Starting to search for path from BetterBlockPos{x=416,y=188,z=832} to JankyComposite Primary: GoalComposite[GoalBlock{x=416,y=188,z=839}, GoalBlock{x=416,y=188,z=838}] Fallback: GoalComposite[]
[19:38:56] [main/INFO]: [CHAT] [Baritone] Took 102ms, 86438 movements considered
[19:38:56] [main/INFO]: [CHAT] [Baritone] Path ends within loaded chunks
[19:38:56] [main/INFO]: [CHAT] [Baritone] Finished finding a path from BetterBlockPos{x=416,y=188,z=832} to JankyComposite Primary: GoalComposite[GoalBlock{x=416,y=188,z=839}, GoalBlock{x=416,y=188,z=838}] Fallback: GoalComposite[]. 3930 nodes considered
[19:38:56] [main/INFO]: [CHAT] [Baritone] bb pls get me some blocks. dirt, netherrack, cobble
[19:38:56] [main/INFO]: [CHAT] [Baritone] Movement returns status UNREACHABLE
...
```

## How to reproduce
* Build a schematic that's super tall and somewhat long on a paper 1.14.4 server.
* Observe it happen around layer >120.