feat: Value will now throw when errors are present

The Value property is now properly encapsulated. When errors are present, the property getter will throw, similar to other properties like Errors or FirstError.

Signed-off-by: Kenny Pflug <kenny.pflug@live.de>

src/ErrorOr/ErrorOr.cs

@@ -56,7 +56,18 @@ private ErrorOr(TValue value)
     /// <summary>
     /// Gets the value.
     /// </summary>
-    public TValue Value => _value!;
+    public TValue Value
+    {
+        get
+        {
+            if (IsError)
+            {
+                throw new InvalidOperationException("The Value property cannot be accessed when errors have been recorded. Check IsError before accessing Value.");
+            }
+
+            return _value;
+        }
+    }
 
     /// <summary>
     /// Gets the first error.

tests/ErrorOr/ErrorOr.InstantiationTests.cs

@@ -144,17 +144,18 @@ public void CreateFromErrorList_WhenAccessingErrorsOrEmptyList_ShouldReturnError
     }
 
     [Fact]
-    public void CreateFromErrorList_WhenAccessingValue_ShouldReturnDefault()
+    public void CreateFromErrorList_WhenAccessingValue_ShouldThrowInvalidOperationException()
     {
         // Arrange
         List<Error> errors = new() { Error.Validation("User.Name", "Name is too short") };
         ErrorOr<Person> errorOrPerson = ErrorOr<Person>.From(errors);
 
         // Act
-        Person value = errorOrPerson.Value;
+        var act = () => errorOrPerson.Value;
 
         // Assert
-        value.Should().Be(default);
+        act.Should().Throw<InvalidOperationException>()
+           .And.Message.Should().Be("The Value property cannot be accessed when errors have been recorded. Check IsError before accessing Value.");
     }
 
     [Fact]
@@ -247,16 +248,17 @@ public void ImplicitCastSingleError_WhenAccessingErrors_ShouldReturnErrorList()
     }
 
     [Fact]
-    public void ImplicitCastError_WhenAccessingValue_ShouldReturnDefault()
+    public void ImplicitCastError_WhenAccessingValue_ShouldThrowInvalidOperationException()
     {
         // Arrange
         ErrorOr<Person> errorOrPerson = Error.Validation("User.Name", "Name is too short");
 
         // Act
-        Person value = errorOrPerson.Value;
+        var act = () => errorOrPerson.Value;
 
         // Assert
-        value.Should().Be(default);
+        act.Should().Throw<InvalidOperationException>()
+           .And.Message.Should().Be("The Value property cannot be accessed when errors have been recorded. Check IsError before accessing Value.");
     }
 
     [Fact]