FIX #4287 SQL error when accessing an unexisting proposal

htdocs/core/class/html.form.class.php

@@ -1026,7 +1026,7 @@ class Form
         $sql = "SELECT re.rowid, re.amount_ht, re.amount_tva, re.amount_ttc,";
         $sql.= " re.description, re.fk_facture_source";
         $sql.= " FROM ".MAIN_DB_PREFIX ."societe_remise_except as re";
-        $sql.= " WHERE fk_soc = ".$socid;
+        $sql.= " WHERE fk_soc = ".(int) $socid;
         if ($filter) $sql.= " AND ".$filter;
         $sql.= " ORDER BY re.description ASC";