(legacy) fix crashreport PHP Warning: htmlspecialchars() expects parameter 1...

(legacy) fix crashreport  PHP Warning:  htmlspecialchars() expects parameter 1 to be string, array given in /usr/local/www/services_dhcp_relay.php on line 185

src/www/services_dhcp_relay.php

@@ -182,7 +182,7 @@ function enable_change(enable_over) {
 									<tr>
 							                        <td width="22%" valign="top" class="vncellreq"><?=gettext("Destination server");?></td>
 							                        <td width="78%" class="vtable">
-							                          <input name="server" type="text" class="formfld unknown" id="server" size="20" value="<?=htmlspecialchars($pconfig['server']);?>" />
+							                          <input name="server" type="text" class="formfld unknown" id="server" size="20" value="<?=!empty($pconfig['server'])?htmlspecialchars($pconfig['server']):"";?>" />
 							                          <br />
 										  <?=gettext("This is the IP address of the server to which DHCP requests are relayed. You can enter multiple server IP addresses, separated by commas. Select \"Proxy requests to DHCP server on WAN subnet\" to relay DHCP packets to the server that was used on the WAN interface.");?>
 							                        </td>