MySQL Exception on OC 8.2.1.4

Hi,

since OC upgrade on 8.2.1 the app doesn't work anylonger.

```
Exception: {
"Exception":"Doctrine\\DBAL\\Exception\\NotNullConstraintViolationException",
"Message": "An exception occurred while executing 'INSERT INTO oc_shorten (uid, shortcode, url) VALUES (?,?,?)' with params [\"xxx\", \"03JUas\", null]:SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'url' cannot be null",
"Code":0,
"Trace":"
#0 \/var\/www\/owncloud\/3rdparty\/doctrine\/dbal\/lib\/Doctrine\/DBAL\/DBALException.php(116): Doctrine\\DBAL\\Driver\\AbstractMySQLDriver->convertException('An exception oc...', Object(Doctrine\\DBAL\\Driver\\PDOException))
#1 \/var\/www\/owncloud\/3rdparty\/doctrine\/dbal\/lib\/Doctrine\/DBAL\/Statement.php(172): Doctrine\\DBAL\\DBALException::driverExceptionDuringQuery(Object(Doctrine\\DBAL\\Driver\\PDOMySql\\Driver), Object(Doctrine\\DBAL\\Driver\\PDOException), 'INSERT INTO oc_...', Array)
#2 \/var\/www\/owncloud\/lib\/private\/db\/statementwrapper.php(73): Doctrine\\DBAL\\Statement->execute(Array)
#3 \/var\/www\/owncloud\/apps\/shorten\/lib\/makeurl.php(38): OC_DB_StatementWrapper->execute(Array)
#4 \/var\/www\/owncloud\/apps\/shorten\/lib\/makeurl.php(58): getShortcode(NULL)
#5 \/var\/www\/owncloud\/apps\/shorten\/controller\/shortenapicontroller.php(38): generateUrl()
#6 [internal function]: OCA\\Shorten\\Controller\\ShortenApiController->makeurl()
#7 \/var\/www\/owncloud\/lib\/private\/appframework\/http\/dispatcher.php(159): call_user_func_array(Array, Array)
#8 \/var\/www\/owncloud\/lib\/private\/appframework\/http\/dispatcher.php(89): OC\\AppFramework\\Http\\Dispatcher->executeController(Object(OCA\\Shorten\\Controller\\ShortenApiController), 'makeurl')
#9 \/var\/www\/owncloud\/lib\/private\/appframework\/app.php(108): OC\\AppFramework\\Http\\Dispatcher->dispatch(Object(OCA\\Shorten\\Controller\\ShortenApiController), 'makeurl')
#10 \/var\/www\/owncloud\/lib\/private\/appframework\/routing\/routeactionhandler.php(45): OC\\AppFramework\\App::main('ShortenApiContr...', 'makeurl', Object(OC\\AppFramework\\DependencyInjection\\DIContainer), Array)
#11 [internal function]: OC\\AppFramework\\routing\\RouteActionHandler->__invoke(Array)
#12 \/var\/www\/owncloud\/lib\/private\/route\/router.php(282): call_user_func(Object(OC\\AppFramework\\routing\\RouteActionHandler), Array)
#13 \/var\/www\/owncloud\/lib\/base.php(851): OC\\Route\\Router->match('\/apps\/shorten\/m...')
#14 \/var\/www\/owncloud\/index.php(39): OC::handleRequest()
#15 {main}",
"File":"\/var\/www\/owncloud\/3rdparty\/doctrine\/dbal\/lib\/Doctrine\/DBAL\/Driver\/AbstractMySQLDriver.php",
"Line":112
}
```

Regards
calis

Start at apps/shorten/lib/makeurl.php:38 and its caller in apps/shorten/controller/shortenapicontroller.php, following the shown INSERT into oc_shorten. Reproduce the /apps/shorten/makeurl request and inspect why the url parameter is null. Done means the request no longer fails with MySQL's not-null constraint exception.

Written by the indexing model from the issue text.