Fix issue with server validation from dictionary configuration where floating point values can be be accessed as doubles or ints (#18508)

* Fix issue with server validation from dictionary configuration where floating point values can be be accessed as doubles or ints.

* Fixed typo in comment.

---------

Co-authored-by: Mole <nikolajlauridsen@protonmail.ch>

src/Umbraco.Core/PropertyEditors/Validators/DictionaryConfigurationValidatorBase.cs

@@ -21,7 +21,7 @@ public abstract class DictionaryConfigurationValidatorBase
             return false;
         }
 
-        if (configuration.TryGetValue(key, out object? obj) && obj is TValue castValue)
+        if (configuration.TryGetValue(key, out object? obj) && TryCastValue(obj, out TValue? castValue))
         {
             value = castValue;
             return true;
@@ -30,4 +30,24 @@ public abstract class DictionaryConfigurationValidatorBase
         value = default;
         return false;
     }
+
+    private static bool TryCastValue<TValue>(object? value, [NotNullWhen(true)] out TValue? castValue)
+    {
+        if (value is TValue valueAsType)
+        {
+            castValue = valueAsType;
+            return true;
+        }
+
+        // Special case for floating point numbers - when deserialized these will be integers if whole numbers rather
+        // than double.
+        if (typeof(TValue) == typeof(double) && value is int valueAsInt)
+        {
+            castValue = (TValue)(object)Convert.ToDouble(valueAsInt);
+            return true;
+        }
+
+        castValue = default;
+        return false;
+    }
 }