Fix breakage introduced in plpgsql CONTINUE patch.

Per Kevin McArthur.

src/pl/plpgsql/src/pl_exec.c

@@ -3,7 +3,7 @@
  *			  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.149 2005/06/26 22:05:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.150 2005/07/28 00:26:30 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -1143,7 +1143,7 @@ exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
 	{
 		PLpgSQL_diag_item	*diag_item = (PLpgSQL_diag_item *) lfirst(lc);
 		PLpgSQL_datum		*var;
-		bool				 isnull;
+		bool				 isnull = false;
 
 		if (diag_item->target <= 0)
 			continue;