After using the clock to look for spelling errors, code samples, or other reports, I decided that your question was the only one that I found on the Internet, and then, after giving it generosity, it looks like I found a solution.
I used this code in my projectname / sass / var / all.scss and it gave the same error you are reporting.
@include panel-ui ( $ui: 'mainmenu', $body-background-color: red );
Then searching for samples (e.g. ext-6.0.1 / examples / modern / addressbook / sass / src / view / Main.scss) I realized that I included it in the wrong file.
Since I wanted to style Ext.Panel, I decided that it should be included in /sass/src/Panel.scss, but the file name should be mapped to a file of my own source. In my case: sass / src / view / main / Menu.scss
Now it compiles and works great.
I assume the problem is that when using srs / Panel.scss, the code simply did not turn on, and when it was done in var / all.scss, it was evaluated before Fashion / Cmd detected the panel-ui definition.
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