In proceedings to set aside an arbitral award for invalidity, the failure to rule on a plea that is in any event manifestly unfounded does not constitute a ground of invalidity under art. 829 of the Code of Civil Procedure, not even in its most serious form: the arbitrators’ decision, though implicitly rejected in the absence of an express ruling, is not open to challenge under the provisions setting out the exhaustive grounds for challenging an award where dismissal of the plea would in any event have been inevitable.