fix(filter): Fixed filtering on nullable datetime

Author: Jamess-Lucass

src/GoatQuery/src/Evaluator/FilterEvaluator.cs

@@ -52,7 +52,9 @@ public static Result<Expression> Evaluate(QueryExpression expression, ParameterE
                             value = Expression.Constant(literal.Value, property.Type);
                             break;
                         case DateLiteral literal:
-                            property = Expression.Property(property, "Date");
+                            property = property.Type == typeof(DateTime?) ?
+                                Expression.Property(Expression.Property(property, "Value"), "Date") :
+                                Expression.Property(property, "Date");
 
                             value = Expression.Constant(literal.Value.Date, property.Type);
                             break;

src/GoatQuery/tests/User.cs

@@ -8,7 +8,7 @@ public record User
     public decimal? BalanceDecimal { get; set; }
     public double? BalanceDouble { get; set; }
     public float? BalanceFloat { get; set; }
-    public DateTime DateOfBirth { get; set; }
+    public DateTime? DateOfBirth { get; set; }
 }
 
 public sealed record CustomJsonPropertyUser : User