Block at -47, 88, 314 is Block{minecraft:stone} but has net.minecraft.server.v1_15_R1.TileEntityDispenser@4ce5b052. Bukkit will attempt to fix this, but there may be additional damage that we cannot recover.

This happens with all kinds of blocks with Inventory

1. you didn't follow the template
2. you can ignore this, nothing is broken, bukkit just likes making noise