JsonLogic v3.1.0 breaks null checks

[ghost]

Environment

• Nuget Package: JsonLogic
• Nuget Version: 3.1.0
• OS: Windows 11 64 Bit
• .Net Target: .net core 3.1

Describe the bug
Operations like "!=", "==" and possible more against or with null are broken after upgrading to v3.1.0. They were working in v3.0.0
See the code snipped in the "To Reproduce" section for an example. The code there throws an exception like this:

Object reference not set to an instance of an object.
   at Json.Logic.Rules.LooseEqualsRule.Apply(JsonNode data, JsonNode contextData)
   at async Program.<Initialize>(?) in :line 17
   at Program.<Main>()

To Reproduce
Code to reproduce in RoslynPad or the likes:

#r "nuget:System.Text.Json/6.0.5"
#r "nuget:JsonLogic/3.1.0"

using System.Text.Json;
using System.Text.Json.Nodes;
using Json.Logic;

var node = JsonNode.Parse(@"
{
        ""=="": [
            {""var"": ""value""},
            null
        ]
}");

var rule = System.Text.Json.JsonSerializer.Deserialize<Rule>(node.ToJsonString());
rule.Apply(JsonNode.Parse("{\"value\": null}"));

Expected behavior
The .Apply() call should return true for the test case

Additional context
The issue doesn't exist in v3.0.0 but in 3.0.0 other things are broken therefore we've upgraded to 3.1.0

[gregsdennis]

Thanks for the report. This seems to be related to say least another issue.

I'll dig in tonight.

[ghost]

Thanks for the report. This seems to be related to say least another issue.

I'll dig in tonight.

Thanks, if you need anything let me know. I'm located in Europe and my day just started :)

[gregsdennis]

Minor suggestion: the .ToJsonString() isn't necessary. JsonNode has a deserialization extension method on it that lets you change

var rule = System.Text.Json.JsonSerializer.Deserialize<Rule>(node.ToJsonString());

to

var rule = node.Deserialize<Rule>();

---

I've replicated the issue, though. Continuing to dig.

[gregsdennis]

Okay. Props to the .Net team for anticipating this one.

By default, the serializer skips the JSON converter for reference types when the value is null and just "deserializes" a null. This was causing the arguments for the == rule to deserialize (expecting a Rule[]) to [ <VariableRule>, null ], and I couldn't handle it in the Rule converter (because it was being skipped).

But they put in a virtual property on the converter base called HandleNull. I've set this to true, and now the Rule converter can handle the null and coerce it to another VariableRule with a null value.

This fixes the issue of throwing the exception, and the rule now returns true.

I'll have an update out shortly.

[ghost]

Thanks a lot! We really appreciate your efforts and especially the very quick turn-around time. It has been a pleasure using your libraries