Serialiser_Engine: Stop throwing error on System.DBNull

[Tom-Kingstone]

NOTE: Depends on

Issues addressed by this PR

Closes #3210

after many hours of searching, finally found out that System.DBNull should serialise as null, so we should stop throwing errors when trying to serialise it.

Test files

3210-DBNullCannotBeSerialised.zip
Run through instructions made by myself in parent issue.

Changelog

Additional comments

[albinber]

No longer running into the error when testing, nice work @Tom-Kingstone!

[albinber]

@BHoMBot check compliance
@BHoMBot check versioning

[bhombot-ci]

@albinber to confirm, the following actions are now queued:

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[Tom-Kingstone]

@BHoMBot check core
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[bhombot-ci]

@Tom-Kingstone to confirm, the following actions are now queued:

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There are 24 requests in the queue ahead of you.

[FraserGreenroyd]

Thanks @Tom-Kingstone and @albinber

To recap some of the work from todays workshop on this, the 'issue' is caused by components in the UI utilising the System.DBNull type for default values as opposed to traditional null. When components are added or deleted, the Grasshopper write method is called to serialise the component in the state it was in, which then causes this issue where our serialiser encounters a System.DBNull and throws an error when it can't serialise it.

This only then caused a problem on the canvas when a larger component, handling a lot of data, intercepts the error recorded and assigns it to that component, rather than the component (deletion) which triggered it. This then gives a confusing and poor UX.

This PR resolves that poor UX by treating items of type System.DBNull as the same as null for serialisation purposes, which I think makes the most logical sense for the time being.

I've run through a few tests on this and it all looks ok from what I can see, so I'm going to merge this for now so that if there are any issues, others can help us spot them via alphas.

Cheers again both 😄

[FraserGreenroyd]

@BHoMBot check serialisation
@BHoMBot check null-handling
@BHoMBot check ready-to-merge

[bhombot-ci]

@FraserGreenroyd to confirm, the following actions are now queued:

• check serialisation
• check null-handling
• check ready-to-merge

There are 3 requests in the queue ahead of you.

[FraserGreenroyd]

@BHoMBot this is a DevOps instruction. I am requesting neutral checks on: unit-tests

[bhombot-ci]

@FraserGreenroyd I have provided neutral checks to the checks requested. These checks will need to be run properly to obtain full results.