Fix multiplication in multiplier

Projects/TerraTech/TerraTech/ObjectFieldMultiplier.cs

@@ -23,6 +23,24 @@ namespace TerraTech {
                 throw new ArgumentException(
                     string.Format("Field {0} does not exist on {1}", fieldName, parentTraverse));
             }
+
+            // Verify TValue is a numeric type
+            if (!IsNumericType(typeof(TValue))) {
+                throw new ArgumentException(string.Format("Type {0} must be a numeric type", typeof(TValue).Name));
+            }
+        }
+
+        private static bool IsNumericType(Type type) {
+            return type == typeof(byte) || type == typeof(sbyte) || type == typeof(short) || type == typeof(ushort) ||
+                   type == typeof(int) || type == typeof(uint) || type == typeof(long) || type == typeof(ulong) ||
+                   type == typeof(float) || type == typeof(double) || type == typeof(decimal);
+        }
+
+        private static TValue MultiplyValues(TValue a, TValue b) {
+            // Convert to double for the multiplication
+            double result = Convert.ToDouble(a) * Convert.ToDouble(b);
+            // Convert back to TValue
+            return (TValue)Convert.ChangeType(result, typeof(TValue));
         }
 
         public TValue GetValue() {
@@ -48,9 +66,7 @@ namespace TerraTech {
 
         public void Apply() {
             try {
-                dynamic originalDynamic = _originalValue;
+                var newValue = MultiplyValues(_originalValue, _multiplier.Value);
-                dynamic multiplierDynamic = _multiplier.Value;
-                var newValue = (TValue)(originalDynamic * multiplierDynamic);
 
                 if (Main.debug.Value)
                     Console.WriteLine("Applying to {0}: {1} * {2} = {3}", _fieldName, _originalValue, _multiplier.Value,