I created an echart displaying a line graph. Now, I'm looking to enhance it by adding gradient colors similar to the image shown below: https://i.sstatic.net/SStjz.png
According to this source, it supports setting gradient colors. However, when I attempted to implement it using the provided code snippet: https://i.sstatic.net/fIqiN.png
I encountered the following error message: https://i.sstatic.net/zSgRu.png
Any suggestions on what steps to take next?
Appreciate any help in advance.