1′‐Phenyl‐2′,3′,5′,6′,7′,7a′‐hexa­hydro­indan‐2‐spiro‐2′‐1H‐pyrrolizine‐3′‐spiro‐11′‐indeno[1,2‐b]quinoxaline‐1,3‐dione. Corrigendum