(auth/ldap) disable error reporting on connect, to prevent api to signal...

(auth/ldap) disable error reporting on connect, to prevent api to signal authentication errors as issues.

exception 'Exception' with message 'Error at /usr/local/opnsense/mvc/app/library/OPNsense/Auth/LDAP.php:236 - ldap_bind(): Unable to bind to server: Invalid credentials (errno=2)' in /usr/local/opnsense/mvc/app/controllers/OPNsense/Base/ApiControllerBase.php:84
Stack trace:
 0 [internal function]: OPNsense\Base\ApiControllerBase->APIErrorHandler(2,

(cherry picked from commit 3fdb5a93)

src/opnsense/mvc/app/library/OPNsense/Auth/LDAP.php

@@ -225,6 +225,13 @@ class LDAP implements IAuthConnector
      */
     public function connect($bind_url, $userdn = null, $password = null, $timeout = 30)
     {
+        $retval = false;
+        set_error_handler(
+            function () {
+                null;
+            }
+        );
+
         $this->closeLDAPHandle();
         $this->ldapHandle = @ldap_connect($bind_url);
 
@@ -235,14 +242,17 @@ class LDAP implements IAuthConnector
             ldap_set_option($this->ldapHandle, LDAP_OPT_PROTOCOL_VERSION, (int)$this->ldapVersion);
             $bindResult = @ldap_bind($this->ldapHandle, $userdn, $password);
             if ($bindResult) {
-                return true;
+                $retval = true;
             } else {
                 syslog(LOG_ERR, 'LDAP bind error (' .  ldap_error($this->ldapHandle).')');
             }
         }
 
-        $this->ldapHandle = null;
-        return false;
+        restore_error_handler();
+        if (!$retval) {
+            $this->ldapHandle = null;
+        }
+        return $retval;
     }
 
     /**