ArgumentNullException: Value cannot be null.[3.1.8]

[gatalskii]

I encounter some annoying problem: when flowgraph selected(showing in unity’s insector) in playmode started to flow lot of same errors. When I deselect the flowgraph file, error emmiting stops.

There’re logs: logs

Unity version: 2020.1.12f1.

Thank you.

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[gatalskii]

Catched some reproduction steps:

1. Let some object a on scene A and attached flowscript on it;

2. Select the script in the project that attached to object(it should shown in the inspector now);

3. Unload scene A, load scene B. Scene B doesn’t contain object a;

4. When B has loaded, then will start error logging every frame. If not, try to point your cursor above inspector, in my case this triggers logging errors too.

P.S. It seems like cached contextObject contains reference on already destroyed object, so IsPartOfRegularPrefab can’t handle this object properly?

[Gavalakis]

Hello there,

Hmm. Can you please clarify what you mean in your Step #2 reproduction?

Do you mean selecting the prefab object “a” that was added in scene A?

Also what version are you using please?

Thank you.

 

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[gatalskii]

I meant you should select FlowScript file in project hierarchy which is attached to the object on the scene.

I’m using the latest version — 3.1.8, but this behaviour keeps from previous version 3.1.6 or maybe earlier.

[Gavalakis]

Hello again and sorry for the late reply!

To fix this, please open up BlackboardEditor.cs file and replace line #103 with this line of code:

options.blockReorder = contextObject != null ? PrefabUtility.IsPartOfRegularPrefab(contextObject) : false;

If you rather want me to send you the file to your registered email account please let me know.

Thank you.

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[gatalskii]

Hello, your solution helped to avoid issue I’ve been describing, but I have another question, do you mind?

Again, when I pick FlowCanvas asset file from Project which already attached to the some object there is some field corresponding to the ran flowscript:

 

But if I destroy my object with FlowScriptController and BlackBoard components field in the picture above will still remain. Is that behaviour appropriate? Thanks.

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[Gavalakis]

Hello again,
I will have to change the inspector there, so that the GameObject variables do not show since they do not belong to the graph. So this is a minor UI bug which I will need to fix. The gameobject variable should not show in both cases (gameobject alive or destroyed).
Thank you for pointing this out to me.

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