Did you created your component in blade file or somewhere else?
Can you share with me the file where you created a component?
Coder And Traveller #tech_lover
I need more information to reproduce this. As from your screenshot, it clearly says authentication is missing. Please log in and pass the latest token to fetch data from the API.
The error which I am seeing is generally a syntax error. It's nothing related to the overriding. Please check the file there is some minor mistake in the file.
It depends on development, if someone only wants to do the CSS stuff then this command is not needed because use can directly do in the resources folder.
However, if you totally want to change the package and make theme from scratch. Then you can create a new package and use that command which you are telling by registering your assets in the provider.
You can create a new sidebar component and replace it with the existing one.
This is the sidebar component
packages/Webkul/Velocity/src/Resources/assets/js/UI/components/sidebar.vue which is registered here
packages/Webkul/Velocity/src/Resources/assets/js/app.js on line number 44.