getName() on null?

I have no idea what is causing this error:

PocketMine-MP Crash Dump Thu Jul 2 10:08:59 EDT 2015

Error: Call to a member function getName() on null
File: /src/pocketmine/level/Level__64bit
Line: 2634
Type: E_ERROR

Code:
[2625] return (int) $this->time;
[2626] }
[2627]
[2628] /**
[2629] * Returns the Level name
[2630] *
[2631] * @return string
[2632] */
[2633] public function getName(){
[2634] return $this->provider->getName();
[2635] }
[2636]
[2637] /**
[2638] * Returns the Level folder name
[2639] *
[2640] * @return string
[2641] */
[2642] public function getFolderName(){
[2643] return $this->folderName;
[2644] }

You have to call the getName function on a Level object. Try

PHP:

$this->getServer()->getLevelByName("name");

Probably a wrongly initialized level?

Just figured it out. I was trying to unload a level, but I ended up using a delayed task to do it which did the trick.

Bump. I'm getting the same error. Every time I try to unload a world, I get this error

Code:

[14:02:45] [Server thread/INFO]: Unloading level "kingoftheladder"

Fatal error: Call to a member function getName() on null in phar://C:/Users/Jack/Desktop/Coding/POCKETMINE/PocketMine-MP/PocketMine-MP.phar/src/pocketmine/level/Level__32bit.php on line 2634

What could be causing this?

Are you sure that is the correct name of the level? Are you using that level later on?