Skip to content

Errata for Invasion of the Alien Ducks

Step 6 - Creating a function to descend sprites.

After completing step 6, shooting a Duck or Apple that is on the top row will result in the "Program Error: sim error: failed to cast on null" being reported. The cause is due to the placement of the final 4 blocks in the outer if block highlighted in the below screen shot.

screen shot

The blocks need moving into the inner if block as shown in this screen shot.

screen shot