src/vs/platform/markers/common/markerService.ts/MarkerStats/_resourceStats
class MarkerStats:	private _resourceStats(resource: URI): MarkerStatistics {
		const result: MarkerStatistics = { errors: 0, warnings: 0, infos: 0, unknowns: 0 };

		// TODO this is a hack
		if (unsupportedSchemas.has(resource.scheme)) {
			return result;
		}

		for (const { severity } of this._service.read({ resource })) {
			if (severity === MarkerSeverity.Error) {
				result.errors += 1;
			} else if (severity === MarkerSeverity.Warning) {
				result.warnings += 1;
			} else if (severity === MarkerSeverity.Info) {
				result.infos += 1;
			} else {
				result.unknowns += 1;
			}
		}

		return result;
	}