Steps:
1- Have a capability.

2 - Get the capability.
Example:

	public static IExample getCapability(Entity entityIn)
	{
		return entityIn.getCapability(CAPABILITY).orElseThrow(NullPointerException::new);
	}

3 - Use an event.

Example:

PlayerTickEvent.

4 - Kill the player. (/ kill)

5 - The game throws NullPointerException.

Edited October 24, 20195 yr by Atila1091
Giving up the post

1 hour ago, Atila1091 said:

Steps:

Have you stepped through the code with the debugger?

I already know what causes the problem:
When the player dies the capability is marked invalid and returns: LazyOptional.empty () ;. I am currently using a static internal method: ForgeEventFactory.gatherCapabilities. 

	public static IExample getCapability(Entity entityIn)
	{
		return ForgeEventFactory.gatherCapabilities(Entity.class, entityIn, null).getCapability(CAPABILITY).orElseThrow(NullPointerException::new);
	}

See the CapabilityProvider class to understand the problem.

44 minutes ago, Atila1091 said:

I already know what causes the problem:
When the player dies the capability is marked invalid and returns: LazyOptional.empty () ;. I am currently using a static internal method: ForgeEventFactory.gatherCapabilities. 

	public static IExample getCapability(Entity entityIn)
	{
		return ForgeEventFactory.gatherCapabilities(Entity.class, entityIn, null).getCapability(CAPABILITY).orElseThrow(NullPointerException::new);
	}

See the CapabilityProvider class to understand the problem.

It was not a good idea to use this internal method. Looks like I'll have to use reflection.

14 hours ago, diesieben07 said:

I believe this was fixed in 1.14.4.

Do not use 1.13.2.

Thanks.