Unreal gives error when line tracing collision

I am currently using Unreal Engine 4.26.
I have been following this tutorial to make a parkour game in Unreal.

I followed the tutorial exactly, and made a walk/jump/double jump game.

However, when I made the wall climbing system, Unreal started giving an error.

The wall climbing still works, but it shows this error when it ends:

Blueprint Runtime Error: "Accessed None trying to read property CallFunc_BreakHitResult_HitActor". Blueprint:  Parkour_BP_Char Function:  Execute Ubergraph Parkour BP Char Graph:  EventGraph Node:  Branch

It has hundreds of copies of that error in the message log.

I would provide my unreal file, but I don’t know how.

Here is the double jump blueprint setup;
Image 1
Image 2
Image 3

(Sorry about 3 images, it’s a large setup.)

Does anyone know how I can solve the error?

Will edit question with more info if needed.