3DModel: Deleting last in-use 3D model breaks editor view and corrupts project

[ToadLobe]

Problem description

Deleting the last model used by a layout object stops that object from being able to render in the editor, even when a new model replaces the old one. If you close the project while in this state, it will fail to reopen with the error:

[Project] Exception opening:  Error: missing model3d 'Duck' in model3d parameter
    at window.xpt.nk (projectResources.js:1:701113)
    at t.KYs (projectResources.js:1:619722)
    at t.bqs (projectResources.js:1:625668)
    at t.lbt (projectResources.js:1:625452)
    at t.nk (projectResources.js:1:603459)
    at window.mht.abt (projectResources.js:1:579810)
    at window.eot.AKs (projectResources.js:1:584097)
    at window.eot.nk (projectResources.js:1:584742)
    at t.nk (projectResources.js:1:572607)
    at Object.Fwi (projectResources.js:1:573481)

Attach a .c3p

Repro.c3p.zip

Steps to reproduce

1. Delete the Duck 3D model
2. Add another model

Or to test project corruption:

1. Delete the Duck 3D model
2. Close the project
3. Reopen the project

Observed result

Despite the model selection dropdown appearing in the object properties with the new model selected, nothing is rendered. If the project is closed it can't be repoened.

Expected result

The newly added model is rendered as the object model. The project can be closed and reopened without corrupting.

More details

Affected browsers/platforms: Repro in chrome

First affected release: Repro in r484

System details

View details

PASTE HERE

[DiegoScirra]

Will be fixed in the next beta.