app//net.minecraft.server.v1_13_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:77)

// This is line 127
public void validateContainers() {
    Set<Location> toRemove = new HashSet<>();
    // this.containers is just a Set<Location>
    for (Location location : this.containers) {
        // This is line 130
        if (!(location.getBlock().getState() instanceof Lockable)) {
            toRemove.add(location);
        }
    }
    for (Location location : toRemove) {
        this.containers.remove(location);
    }
}