empty loadingUIText setter for null engine

[nekochanoide]

using null engine and setting loading ui text to it causes crash...
added 'do nothing' setter for loadingUIText

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We have noticed you haven't changes the "what's new.md" file. If your update is important (a bug fix, a new feature), please make sure to update the what's new file in the base directory and commit the changes.

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Snapshot stored with reference name:
refs/pull/12320/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12320/merge/index.html

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https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12320/merge/index.html#WGZLGJ#4600

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[RaananW]

The setter is being inherited from the Engine class, and is located in NullEngine as well. I gues the issue is that loadingScreen is gone?

[nekochanoide]

yes. no loadingScreen in null engine but NullEngine type says that it's okey to use loadingUIText, so code in Engine throws 'can't access loadingUIText of undefined'.

[nekochanoide]

to break current version execute this

let e = new BABYLON.NullEngine();
e.loadingUIText = "hello";

[azure-pipelines]

We have noticed you haven't changes the "what's new.md" file. If your update is important (a bug fix, a new feature), please make sure to update the what's new file in the base directory and commit the changes.