src/vs/workbench/browser/parts/editor/editorWithViewState.ts/AbstractEditorWithViewState/getViewState
class AbstractEditorWithViewState:	override getViewState(): T | undefined {
		const input = this.input;
		if (!input || !this.tracksEditorViewState(input)) {
			return; // need valid input for view state
		}

		const resource = this.toEditorViewStateResource(input);
		if (!resource) {
			return; // need a resource for finding view state
		}

		return this.computeEditorViewState(resource);
	}