GP event data fix

PlayerEventHandler.java:600

Material clickedBlockType = clickedBlock.getType();

if (clickedBlockType == null) {
    Claim claim = this.dataStore.getClaimAt(clickedBlock.getLocation(), false, null);
    if (claim != null) {
        String noAccessReason = claim.allowAccess(player);
        if (noAccessReason != null) {
            event.setCancelled(true);
            GriefPrevention.sendMessage(player, TextMode.Err, noAccessReason);
        }
    }
    return;
}