Merge pull request '#3. /JL' (#5) from 0.0.4 into main

Reviewed-on: #5

tetris-game/scripts/board.gd

@@ -201,16 +201,27 @@ func _lock_piece() -> void:
 
 func _clear_full_lines() -> int:
 	var cleared_lines := 0
-	for y in range(BOARD_HEIGHT - 1, -1, -1):
+	var y := BOARD_HEIGHT - 1
+
+	while y >= 0:
 		var is_full := true
 		for x in range(BOARD_WIDTH):
 			if grid[y][x] == "":
 				is_full = false
 				break
+
 		if is_full:
+			# Remove this row and drop everything above it down by 1
 			_drop_lines_above(y)
 			cleared_lines += 1
-			y += 1  # re-check same row index (now replaced)
+			# IMPORTANT:
+			# Do NOT change y here.
+			# After dropping, a new row has moved into index y,
+			# so we re-check the same y in the next loop iteration.
+		else:
+			# Only move up when the current row was not cleared
+			y -= 1
+
 	return cleared_lines
 	
 func _drop_lines_above(row: int) -> void: