FIX 17.0 fatal when updating recurring supplier invoice line with php…

…8 ($remise_percent is '' instead of 0) (#31713)

htdocs/fourn/facture/card-rec.php

@@ -778,7 +778,7 @@
 			$special_code = 3;
 		}
 
-		$remise_percent = price2num(GETPOST('remise_percent'), '', 2);
+		$remise_percent = price2num(GETPOST('remise_percent'), '', 2) ?: 0;
 
 		// Check minimum price
 		$productid = GETPOST('productid', 'int');