A quick fix for an existing bug that was just found where a potion with the right ID matching a map that the potion was near can cause the creative pick block function to throw an error and stall out an entire player processing thread.

This is extremely unlikely, but could happen. In addition to the fix, a safeguard has been put in place to prevent this from stalling out the processing thread if there are issues in the future.

EDIT: For some reason Spigot isn't uploading the updated JAR file. To fix this I'm reposting the update and I will check the JAR immediately; go ahead and re-download this if you want the fix or have any issues.