In the last update (1.7.0) the DisplayInspectorAttribute.cs script uses Null Coalescing Assignment, this causes an incompatibility with old versions of unity since this is a feature of c# 8.0 onwards. It has been changed to a compatible code to be able to use the latest update.
In the last update (1.7.0) the DisplayInspectorAttribute.cs script uses Null Coalescing Assignment, this causes an incompatibility with old versions of unity since this is a feature of c# 8.0 onwards. It has been changed to a compatible code to be able to use the latest update.
More info about Null Coalescing Assignment: https://learn.microsoft.com/dotnet/csharp/language-reference/proposals/csharp-8.0/null-coalescing-assignment