Fix psalm issues related to the user backend

- Reflect the actual return value returned by the implementation in the
  the interface. E.g. IUser|bool -> IUser|false
- Remove $hasLoggedIn parameter from private countUser implementation.
  Replace the two call with the equivalent countSeenUser
- getBackend is nuallable, add this to the interface
- Use backend interface to make psalm happy about call to undefined
  methods. Also helps with getting rid at some point of the old
  implementActions

Signed-off-by: Carl Schwan <carl@carlschwan.eu>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/private/User/Database.php b/lib/private/User/Database.php
index a9464c27085..4821a2fc632 100644
--- a/lib/private/User/Database.php
+++ b/lib/private/User/Database.php
@@ -275,7 +275,7 @@ class Database extends ABackend implements
 			->setMaxResults($limit)
 			->setFirstResult($offset);
 
-		$result = $query->execute();
+		$result = $query->executeQuery();
 		$displayNames = [];
 		while ($row = $result->fetch()) {
 			$displayNames[(string)$row['uid']] = (string)$row['displayname'];