iron.Scene.spawnObject() fails with error when `Stream Scene` is enabled

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**Description**
Logic Node Spawn Object Error
```
Falling back to the system's preferred WASAPI mix format.
Trace: TypeError: Cannot read property 'name' of null
at :6500:19
at iron_Scene.returnObjectLoaded (:6834:3)
at iron_Scene.returnObject (:6801:9)
at iron_Scene.streamMeshObject (:6683:8)
at iron_Scene.createMeshObject (:6745:9)
at :6547:16
at Function.iron_data_Data.getMaterial (:4854:3)
at iron_Scene.createObject (:6542:21)
at spawnObjectTree (:6489:11)
at iron_Scene.spawnObject (:6505:3)
Info: Saved "spawnError.blend"
```

**To Reproduce**
Steps to reproduce the behavior.

**Expected behavior**

**System**
Blender: 2.83.12
Armory: 2021.3
OS: Windows 10 Pro 64bit
Graphics card: Raden R9 270X

**Test File**
[spawnError.zip](https://github.com/armory3d/armory/files/6074608/spawnError.zip)

Open the supplied spawnError.blend from spawnError.zip and reproduce the failure with Stream Scene enabled. Start from the stack-trace entry points iron_Scene.spawnObject, createObject, streamMeshObject, and returnObjectLoaded; compare behavior with streaming disabled. Done means spawning no longer produces the reported null-name TypeError.

Written by the indexing model from the issue text.