[TimePicker] Add null check for empty string

src/Core/Components/DateTime/FluentTimePicker.razor.cs

@@ -26,7 +26,7 @@ protected override bool TryParseValueFromString(string? value, out DateTime? res
         }
         else
         {
-            result = Value?.Date;
+            result = string.IsNullOrWhiteSpace(value) ? null : Value?.Date;
         }
 
         validationErrorMessage = null;

tests/Core/DateTime/FluentTimePickerTests.cs

@@ -55,6 +55,19 @@ public void FluentTimePicker_TryParseValueFromString(string? value, string? time
         }
     }
 
+    [Fact]
+    public void FluentTimePicker_EmptyStringToNull()
+    {
+        // Arrange
+        var picker = new TestTimePicker();
+
+        // Act
+        var _ = picker.CallTryParseValueFromString(string.Empty, out var resultDate, out var _);
+
+        // Assert
+        Assert.Null(resultDate);
+    }
+
     // Temporary class to expose protected method
     private class TestTimePicker : FluentTimePicker
     {