Fix phpdoc

app/Auth/DatabaseAuth.php

@@ -90,7 +90,7 @@ class DatabaseAuth extends Base implements PasswordAuthenticationProviderInterfa
      * Get user object
      *
      * @access public
-     * @return null|\Kanboard\User\DatabaseUserProvider
+     * @return \Kanboard\User\DatabaseUserProvider
      */
     public function getUser()
     {

app/Auth/GithubAuth.php

@@ -84,7 +84,7 @@ class GithubAuth extends Base implements OAuthAuthenticationProviderInterface
      * Get user object
      *
      * @access public
-     * @return null|GithubUserProvider
+     * @return GithubUserProvider
      */
     public function getUser()
     {

app/Auth/GitlabAuth.php

@@ -84,7 +84,7 @@ class GitlabAuth extends Base implements OAuthAuthenticationProviderInterface
      * Get user object
      *
      * @access public
-     * @return null|GitlabUserProvider
+     * @return GitlabUserProvider
      */
     public function getUser()
     {

app/Auth/GoogleAuth.php

@@ -84,7 +84,7 @@ class GoogleAuth extends Base implements OAuthAuthenticationProviderInterface
      * Get user object
      *
      * @access public
-     * @return null|GoogleUserProvider
+     * @return GoogleUserProvider
      */
     public function getUser()
     {

app/Auth/RememberMeAuth.php

@@ -66,7 +66,7 @@ class RememberMeAuth extends Base implements PreAuthenticationProviderInterface
      * Get user object
      *
      * @access public
-     * @return null|DatabaseUserProvider
+     * @return DatabaseUserProvider
      */
     public function getUser()
     {

app/Auth/ReverseProxyAuth.php

@@ -67,7 +67,7 @@ class ReverseProxyAuth extends Base implements PreAuthenticationProviderInterfac
      * Get user object
      *
      * @access public
-     * @return null|ReverseProxyUserProvider
+     * @return ReverseProxyUserProvider
      */
     public function getUser()
     {