namespace App\Test\SomeNamespace;

class MyNamespacedClass
{
}

namespace App\Entity;

use App\Test\SomeNamespace as TestSomeNamespace;

class MyClass
{
    public function __construct()
    {
        $object = new TestSomeNamespace\MyNamespacedClass();
    }
}

In NameScope.php line 50:
  [ErrorException]                                    
  Warning: Undefined array key "MyNamespacedClass"

    public function resolveStringName(string $name): string
    {
        if (0 === strpos($name, '\\')) {
            return ltrim($name, '\\');
        }

        $nameParts = explode('\\', $name);
        if (isset($this->uses[$nameParts[0]])) {
            if (1 === \count($nameParts)) {
                return $this->uses[$nameParts[0]];
            }
            array_shift($nameParts);

            return sprintf('%s\\%s', $this->uses[$nameParts[0]], implode('\\', $nameParts));
        }

        if (null !== $this->namespace) {
            return sprintf('%s\\%s', $this->namespace, $name);
        }

        return $name;
    }

    public function resolveStringName(string $name): string
    {
        if (0 === strpos($name, '\\')) {
            return ltrim($name, '\\');
        }

        $nameParts = explode('\\', $name);
        if (isset($this->uses[$nameParts[0]])) {
            if (1 === \count($nameParts)) {
                return $this->uses[$nameParts[0]];
            }
            $use = array_shift($nameParts);

            return sprintf('%s\\%s', $use, implode('\\', $nameParts));
        }

        if (null !== $this->namespace) {
            return sprintf('%s\\%s', $this->namespace, $name);
        }

        return $name;
    }