Clean up some Coverity complaints about commit 0bf3ae88.

The two get_tle_by_resno() calls introduced by this commit lacked any
check for a NULL return, unlike any other calls of that function anywhere
in our tree.  Coverity quite properly complained about it.  Also fix a
misindented line in process_query_params(), which Coverity also complained
about on the grounds that the bad indentation suggested possible programmer
misinterpretation.

contrib/postgres_fdw/deparse.c

@@ -1356,6 +1356,10 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
 		int			attnum = lfirst_int(lc);
 		TargetEntry *tle = get_tle_by_resno(targetlist, attnum);
 
+		if (!tle)
+			elog(ERROR, "attribute number %d not found in UPDATE targetlist",
+				 attnum);
+
 		if (!first)
 			appendStringInfoString(buf, ", ");
 		first = false;

contrib/postgres_fdw/postgres_fdw.c

@@ -2119,6 +2119,10 @@ postgresPlanDirectModify(PlannerInfo *root,
 
 			tle = get_tle_by_resno(subplan->targetlist, attno);
 
+			if (!tle)
+				elog(ERROR, "attribute number %d not found in subplan targetlist",
+					 attno);
+
 			if (!is_foreign_expr(root, baserel, (Expr *) tle->expr))
 				return false;
 
@@ -3305,6 +3309,7 @@ process_query_params(ExprContext *econtext,
 			param_values[i] = NULL;
 		else
 			param_values[i] = OutputFunctionCall(&param_flinfo[i], expr_value);
+
 		i++;
 	}