Unable to upload 3D objects

[daxxterity]

Description
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://hubs.mozilla.com/scenes/BPtCGCW/just-moon
2. Click on 'create a room with this scene' - 'join room' - 'accept' - 'enter room'
3. Once in the room, click on the 'place' icon, select '3D Model'
4. Then top right selection: 'Custom URL or file'
5. This turns the bottom bar white, and no further action is possible.

Expected behavior
I expected to click on 'upload 3D model' would open a selection dialogue box, to select a local 3D file from my computer to upload.

Screenshots
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Hardware

• Device: Desktop
• OS: Windows
• Browser: Chrome

Additional context
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[keianhzo]

Fixed by #6135