Fix plperl crash with list value return for an array result type.

Reported by Michael Fuhr, fixed by Andrew Dunstan.

src/pl/plperl/plperl.c

@@ -33,7 +33,7 @@
  *	  ENHANCEMENTS, OR MODIFICATIONS.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plperl/plperl.c,v 1.85 2005/07/12 01:16:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plperl/plperl.c,v 1.86 2005/07/12 20:35:42 tgl Exp $
  *
  **********************************************************************/
 
@@ -1020,8 +1020,8 @@ plperl_func_handler(PG_FUNCTION_ARGS)
         /* Return a perl string converted to a Datum */
         char *val;
  
-
-        if (prodesc->fn_retisarray && SvTYPE(SvRV(perlret)) == SVt_PVAV)
+        if (prodesc->fn_retisarray && SvROK(perlret) &&
+			SvTYPE(SvRV(perlret)) == SVt_PVAV)
         {
             array_ret = plperl_convert_to_pg_array(perlret);
             SvREFCNT_dec(perlret);