Prevent a Rhino crash when an old type is deserialised in the CreateCustomObject component

[epignatelli]

Issues addressed by this PR

Closes #396

Rhino crashes altogether if you open a script with a CustomObjecy component that serialised a Type that doesn't exist anymore in the BHoM.

Test files

@IsakNaslundBh would you mind using the file that triggered the issue in the first place?

Changelog

• Make sure that Engine.Grasshopper.Query.Type(this IGH_Param param, Caller caller = null) never returns null.

Additional comments

This is quite critical, since it is crashing the whole Rhino.

[epignatelli]

From the Sprint Closure call @IsakNaslundBh to have a go with the script creating the issue

[epignatelli]

@IsakNaslundBh shall we have a look at this together, tomorrow morning, in order to close it?

[adecler]

I am overall happy with that PR except for the one change I requested.

It is important to note that this happens because OnGrasshopperUpdates is called when the component is deleted, which is questionable. This is by our own design:

public class CreateCustomComponent : CallerComponent, IGH_VariableParameterComponent
    {
        /*******************************************/
        /**** Properties                        ****/
        /*******************************************/

        public override Caller Caller { get; } = new CreateCustomCaller();


        /*******************************************/
        /**** Constructors                      ****/
        /*******************************************/

        public CreateCustomComponent() : base()
        {
            this.Params.ParameterChanged += OnGrasshopperUpdates;
        }

So we might want to find an event more suitable than ParameterChanged or a way to differentiate the case where the component is deleted.

I would recommend sticking to this fix for now but raising another issue to investigate further.

[adecler]

This one needs to stay a return as it doesn't belong to the same if-else chain as the rest.

[IsakNaslundBh]

Updated the code to @adecler s comments.

This solves the problem for me and stops the crash.

[adecler]

LGTM now