[TimePicker] Add null check for empty string

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

@@ -20,7 +20,11 @@ protected override bool TryParseValueFromString(string? value, out DateTime? res
     {
         DateTime currentValue = Value ?? DateTime.MinValue;
 
-        if (value != null && DateTime.TryParse(value, out var valueConverted))
+        if (string.IsNullOrWhiteSpace(value))
+        {
+            result = null;
+        }
+        else if (value != null && DateTime.TryParse(value, out var valueConverted))
         {
             result = currentValue.Date + valueConverted.TimeOfDay;
         }

tests/Core/DateTime/FluentTimePickerTests.cs

@@ -55,6 +55,24 @@ public void FluentTimePicker_TryParseValueFromString(string? value, string? time
         }
     }
 
+    [Fact]
+    public void FluentTimePicker_EmptyStringToNull()
+    {
+        // Arrange
+        var picker = new TestTimePicker()
+        {
+            Value = System.DateTime.Today,   // Default date 
+        };
+
+        // Set a value
+        picker.CallTryParseValueFromString("01:23", out var initialDate, out var _);
+        Assert.Equal("01:23:00", initialDate?.ToString("HH:mm:ss"));
+
+        // Reset
+        picker.CallTryParseValueFromString(string.Empty, out var resultDate, out var _);
+        Assert.Null(resultDate?.ToString("HH:mm:ss"));
+    }
+
     // Temporary class to expose protected method
     private class TestTimePicker : FluentTimePicker
     {