Exceeds in health (Causes an error)

Hi, I have currently been watching your tutorials and I love the detailed examples and explanation of your lessons. I have come up with a problem however and I hope you can help me fix it as soon as possible. The error (https://pastebin.com/LD2zL1gy) basically states that when I click the emerald block and I have full health, it is not possible to add more health to the player. I know I can ask this question on Spigot but I would like you to edit your episode 4 so others will not get this error as they are learning. Thank you so much and good luck on Youtube!

[TheAnarchistDev]

Did you make sure that you added in if(player.getHealth()!=20)
if you didn't then thats why you're getting that error