Loading chunk with invalid item causes a crash

[PrimusLV]

Issue description

For some reason sometimes when porting worlds from PC version or maybe converting format types. the item entities can be written on chunk nbt file wrong and cause crash when loading them.

Steps to reproduce the issue

I Don't know and don't want to.

OS and versions

• PocketMine-MP: Starting from 1.4 and up

Crashdump, backtrace or other files

I added some debug messages in Item.php inside initEntity() and this is the output when invalid entity tries to get loaded.

tried to spawn invalid item entity (minecraft:wooden_axe:0:1) at Position(level=mines,x=-226.93924904777,y=74.661162516132,z=113.17553093388)
tried to spawn invalid item entity (minecraft:glass_pane:0:1) at Position(level=mines,x=-227.12765333584,y=74.908027488115,z=113.33313738153)

I added temporary workaround for this

if(!$this->namedtag->Item->id instanceof IntTag) {
    $this->level->removeEntity($this);
    return;
}

But this code above doesn't remove the entity record from nbt file.

This is the full error from console.

[22:56:03] [Server thread/CRITICAL]: TypeError: "Argument 1 passed to pocketmine\item\Item::get() must be of the type integer, string given, called in /home/primus/DevField/src/pocketmine/nbt/NBT.php on line 110" (EXCEPTION) in "/src/pocketmine/item/Item" at line 283
[22:56:03] [Server thread/EMERGENCY]: An unrecoverable error has occurred and the server has crashed. Creating a crash dump
[22:56:03] [Server thread/EMERGENCY]: Please upload the "/home/primus/DevField/CrashDump_Mon_Oct_17-22.56.03-EEST_2016.log" file to the Crash Archive and submit the link to the Bug Reporting page. Give as much info as you can.

And this is the dump string of that Item entity

["id"]=>
  object(pocketmine\nbt\tag\StringTag)#11871 (2) {
    ["__name":protected]=>
    string(2) "id"
    ["value":protected]=>
    string(17) "minecraft:feather"
  }
  ["Count"]=>
  object(pocketmine\nbt\tag\ByteTag)#11872 (2) {
    ["__name":protected]=>
    string(5) "Count"
    ["value":protected]=>
    int(1)
  }
  ["Damage"]=>
  object(pocketmine\nbt\tag\ShortTag)#11873 (2) {
    ["__name":protected]=>
    string(6) "Damage"
    ["value":protected]=>
    int(0)
  }

[dktapps]

Is that a client or server crash?

[PrimusLV]

Server

[dktapps]

Can I ask what version of MC PC this world was generated with?

[PrimusLV]

I got this world from my friend so I don't know. However I'll try to find out but for now, Great job.