Analyzer : Inherited properties don't work when extending a local variable

[Lookwe69]

Checklist

• [x] Did you run the analyzer with the --dev flag to get more information?
• [x] Did you create a minimal reproduction in the playground?

Playground: https://custom-elements-manifest.netlify.app/?source=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%3D%3D&library=litelement

TLDR: When you do something like:

const BaseClass = mixinFunc(HTMLElement);

class MyElement extends BaseClass { ... }

The inherit properties never get added to the custom elements manifest. You must use :

class MyElement extends mixinFunc(HTMLElement) { ... }

The problem is, with a lot of mixin, it easier to read with a separate variable.

const BaseClass = mixinTooltipChart(
	mixinGridChart(mixinLegendChart<typeof Chart<LineChartOption, LineChartData>>(Chart)),
);

export class LineChart extends BaseClass { ... }

Expected behavior It must be possible to create a separate variable before extending the class.