Hi, I am having trouble with te behavior of my submissions. Everything runs fine within both the playground and the runtime environment but once I submit it, it will give me a Runtime error:\n\n`Line 24: AttributeError: \'NoneType\' object has no attribute \'val\'`\nHere\'s the link to my playground: https://leetcode.com/playground/77cjqstU\n\nAny help would be appreciated.\nThanks and best!

Hi, I am having trouble with te behavior of my submissions. Everything runs fine within both the playground and the runtime environment but once I submit it, it