sym2 IF-statement gives error "call to undefined function"

I have an issue with my IF-statement, apparently.

Inside a symfony2 controller I have the following PHP:

        foreach($all as $t) {
            if ( ($end == null) || ($t->getDate()->format('Y-m-d') <= $end->format("Y-m-d")) ) {
                if ( ($start == null) || ($t->getDate()->format('Y-m-d') >= $start->format("Y-m-d")) ) {    
                $subset[] = $t;
                }
            }
        }

I get this for an error message:

FatalErrorException: Error: Call to undefined function App\Bundle\Controller\ () in www/App/src/App/Bundle/Controller/TransactionController.php line 59

So somewhere in my if statement it tries to run a sym2 controller? I am lost...

both $start and $end are valid dateTime objects, so are each $date on the $t objects.

If I comment the second IF-statement out like this, it runs without errors.

        foreach($all as $t) {
            if ( ($end == null) || ($t->getDate()->format('Y-m-d') <= $end->format("Y-m-d")) ) {
                /*
                if ( ($start == null) || ($t->getDate()->format('Y-m-d') >= $start->format("Y-m-d")) ) {    
                $subset[] = $t;
                }
                */
            }
        }

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Addition: Line 59 which the error points to is the line where the second if statement condition is stated.