NodeJS : Firebase - TypeError: Path must be a string. Received undefined

NodeJS : Firebase - TypeError: Path must be a string. Received undefined
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

I promised to reveal a secret feature to you, and now it's time to share it.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
After that, type the word 'awesome' on your keyboard.
It will change your youtube progress bar into a flashing rainbow.

Let me give you a quick introduction about myself,
Hey, I'm known as Delphi.
I am happy to help you with your questions.
NodeJS : Firebase - TypeError: Path must be a string. Received undefined
I am happy to answer more specific questions, so please feel free to comment or chat with me.
If you have an answer or any relevant information to share, please comment below.
Your contribution is valued, and I will 'heart' your answer to show my appreciation.
NodeJS be undefined a : Path must TypeError: string. - Firebase Received