Fix a segfault that followed a malloc failure introduced by (6527). (CVS 6532)

FossilOrigin-Name: 08e71b114087cfddd36c066265982172fcb41c9a

src/where.c

@@ -16,7 +16,7 @@
 ** so is applicable.  Because this module is responsible for selecting
 ** indices, you might also think of this module as the "query optimizer".
 **
-** $Id: where.c,v 1.383 2009/04/21 09:02:47 danielk1977 Exp $
+** $Id: where.c,v 1.384 2009/04/21 17:23:05 danielk1977 Exp $
 */
 #include "sqliteInt.h"
 
@@ -1755,6 +1755,9 @@ static void bestVirtualIndex(
   if( pIdxInfo==0 ){
     *ppIdxInfo = pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pOrderBy);
   }
+  if( pIdxInfo==0 ){
+    return;
+  }
 
   /* At this point, the sqlite3_index_info structure that pIdxInfo points
   ** to will have been initialized, either during the current invocation or