Enable IJSObjectReference to handle null/undefined values

[rolandVi]

Enable IJSObjectReference to handle null/undefined values

Problem

Currently, calling DotNet.createJSObjectReference(null) or DotNet.createJSObjectReference(undefined) throws an error: This forces developers to write workaround code when JavaScript functions might return null/undefined values.

Solution

Modified createJSObjectReference to handle null/undefined values by returning a special sentinel object with __jsObjectId: -1 instead of throwing an error. The .NET side JSON converter recognizes this sentinel value and returns null for the IJSObjectReference?.

Changes

• JavaScript side: createJSObjectReference() now accepts null/undefined and returns {__jsObjectId: -1}
• .NET side: JSObjectReferenceJsonConverter recognizes the -1 sentinel and returns null
• Disposal: Updated disposeJSObjectReference() to safely handle null references (skip disposal for id -1)

Benefits

• Non-breaking change: Converts from exception to success

Fixes #52070

[oroztocil]

Please check that you get an expected result when you do var result = await JS.GetValueAsync<IJSObjectReference>("someProp"); in both cases:

• When someProp is defined in the scope with value set to null or undefined.
• When someProp is not defined in the scope.

[oroztocil]

Nice! 🚀