fix(database): Cast users count to integer

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

lib/private/User/Database.php

@@ -487,9 +487,12 @@ class Database extends ABackend implements
 		$query = $dbConn->getQueryBuilder();
 		$query->select($query->func()->count('uid'))
 			->from($this->table);
-		$result = $query->executeQuery();
+		$result = $query->executeQuery()->fetchOne();
+		if ($result === false) {
+			return false;
+		}
 
-		return $result->fetchOne();
+		return (int)$result;
 	}
 
 	/**

tests/lib/User/DatabaseTest.php

@@ -25,6 +25,9 @@ class DatabaseTest extends Backend {
 	/** @var IEventDispatcher|MockObject */
 	private $eventDispatcher;
 
+	/** @var \OC\User\Database */
+	protected $backend;
+
 	public function getUser() {
 		$user = parent::getUser();
 		$this->users[] = $user;
@@ -139,4 +142,14 @@ class DatabaseTest extends Backend {
 		$result = $this->backend->getDisplayNames('@nextcloud.COM');
 		$this->assertCount(2, $result);
 	}
+
+	public function testUserCount(): void {
+		$base = $this->backend->countUsers() ?: 0;
+		$users = $this->backend->getUsers();
+		self::assertEquals($base, count($users));
+
+		$user = $this->getUser();
+		$this->backend->createUser($user, $user);
+		self::assertEquals($base + 1, $this->backend->countUsers());
+	}
 }