Add null check and refine preconditions for on-ground shortcut.

NCPCompat/src/main/java/fr/neatmonster/nocheatplus/utilities/PlayerLocation.java

@@ -446,9 +446,11 @@ public boolean isOnGround() {
 				final long flags = BlockProperties.getBlockFlags(id);
 				if ((flags & BlockProperties.F_GROUND) != 0 && (flags & BlockProperties.F_VARIABLE) == 0){
 					final double[] bounds = blockCache.getBounds(blockX, bY, blockZ);
-					if (BlockProperties.collidesBlock(blockCache, x, minY - yOnGround, z, x, minY, z, blockX, bY, blockZ, id, bounds, flags)){
+					// Check collision if not inside of the block. [Might be a problem for cauldron or similar + something solid above.]
+					if (bounds != null && y - bY >= bounds[4] && BlockProperties.collidesBlock(blockCache, x, minY - yOnGround, z, x, minY, z, blockX, bY, blockZ, id, bounds, flags)){
 						// TODO: passable vs maxY ?
 						if (!BlockProperties.isPassableWorkaround(blockCache, blockX, bY, blockZ, minX - blockX, minY - yOnGround - bY, minZ - blockZ, id, maxX - minX, yOnGround, maxZ - minZ,  1.0)){
+							// TODO: Might have to exclude on base of maxY, for case of being inside of blocks doors etc. 
 							onGround = true;
 						}
 					}