src/vs/workbench/contrib/scm/browser/dirtydiffDecorator.ts/DirtyDiffWorkbenchController/onDidChangeDiffWidthConfiguration
class DirtyDiffWorkbenchController:	private onDidChangeDiffWidthConfiguration(): void {
		let width = this.configurationService.getValue<number>('scm.diffDecorationsGutterWidth');

		if (isNaN(width) || width <= 0 || width > 5) {
			width = 3;
		}

		this.setViewState({ ...this.viewState, width });
	}