Prevent SQL error message in case of error

`\OC\User\Database::createUser` can throw a PHP exception in case the UID is longer than
permitted in the database. This is against it's PHPDocs and we should cast this to `false`,
so that the regular error handling triggers in.

The easiest way to reproduce is on MySQL:

1. Create user `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` in admin panel
2. Create user `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa` in admin panel again
3. See SQL exception as error message

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/private/User/Manager.php b/lib/private/User/Manager.php
index 8f3c98d4b5e..6b6c10ab295 100644
--- a/lib/private/User/Manager.php
+++ b/lib/private/User/Manager.php
@@ -349,7 +349,10 @@ class Manager extends PublicEmitter implements IUserManager {
 		}
 
 		$this->emit('\OC\User', 'preCreateUser', [$uid, $password]);
-		$backend->createUser($uid, $password);
+		$state = $backend->createUser($uid, $password);
+		if($state === false) {
+			throw new \InvalidArgumentException($l->t('Could not create user'));
+		}
 		$user = $this->getUserObject($uid, $backend);
 		if ($user instanceof IUser) {
 			$this->emit('\OC\User', 'postCreateUser', [$user, $password]);