That would most likely be due to the GetWorld() part of it. Whenever you use GetWorld(), it’s best to check to make sure that GetWorld() isn’t returning a null pointer first. This would explain why the editor is crashing when it opens, as it tries to call this function before the level is initialized, resulting in a null pointer being given, causing the assert.
Edit: To check, just surround your statement that is using GetWorld() with an if statement like so:
if(GetWorld())
{
//Statement that uses GetWorld()
}