src/vs/workbench/contrib/typeHierarchy/common/typeHierarchy.ts/TypeHierarchyModel/provideSupertypes
class TypeHierarchyModel:	async provideSupertypes(item: TypeHierarchyItem, token: CancellationToken): Promise<TypeHierarchyItem[]> {
		try {
			const result = await this.provider.provideSupertypes(item, token);
			if (isNonEmptyArray(result)) {
				return result;
			}
		} catch (e) {
			onUnexpectedExternalError(e);
		}
		return [];
	}