FCLT#53703 Je moet de velden natuurlijk nog leeg kunnen maken

svn path=/Website/branches/v2018.1/; revision=38903

APPL/PRS/prs_edit_perslid_save.asp

@@ -62,7 +62,7 @@ if (prsauthparams.writesys || (S("prs_mgt_edit_login")?xfunc.canWrite("WEB_FACMG
 {
     // Check for uniqueness of OSLOGIN and OSLOGIN2 among existing OSLOGIN and OSLOGIN2
     var login  = getFParam("prs_oslog");
-    if (login)
+    if (typeof login == "string")
     {
         var logSql = "SELECT '' FROM prs_perslid"
                    + " WHERE (UPPER (prs_perslid_oslogin) = " + safe.quoted_sql_upper(login)
@@ -76,7 +76,7 @@ if (prsauthparams.writesys || (S("prs_mgt_edit_login")?xfunc.canWrite("WEB_FACMG
         logoRs.Close();
     }
     var login2 = getFParam("prs_oslog2");
-    if (login2)
+    if (typeof login2 == "string")
     {
         var logSql = "SELECT '' FROM prs_perslid"
                    + " WHERE (UPPER (prs_perslid_oslogin) = " + safe.quoted_sql_upper(login2)