JavaScript : Uncaught TypeError: Cannot read property 'toLowerCase' of undefined

JavaScript : Uncaught TypeError: Cannot read property 'toLowerCase' of 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, Ensure that the video is playing before proceeding.
After that, type the word 'awesome' on your keyboard.
The progress bar on YouTube will be altered to a flashing rainbow.

Let me give you a brief introduction of who I am,
Welcome, I'm Delphi.
I can provide you with assistance to help you answer your questions.
JavaScript : Uncaught TypeError: Cannot read property 'toLowerCase' of undefined
Let me know if you have more specific questions or concerns by leaving a comment or starting a chat.
Please feel free to leave a comment below if you have an answer or insights on the answer.
A 'heart' from me will be given as a sign of appreciation for your answer.
property read of TypeError: Cannot JavaScript : 'toLowerCase' Uncaught undefined