Property drawers in DLL cause errors

Hi.
I have a simple property drawer code put in DLL.

Code (csharp):

1. [CustomPropertyDrawer(typeof(ToggleButtonAttribute))]
2. public class ToggleButtonAttributeDrawer : PropertyDrawer
3. {
4.    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
5.    {
6.       ToggleButtonAttribute attr = attribute as ToggleButtonAttribute;
7.  
8.       bool value = property.boolValue;
9.       string nameString = attr.NameString == null ? label.text : attr.NameString;
10.       string valueString = value ? attr.TrueString : attr.FalseString;
11.  
12.       Rect btnPos = EditorGUI.PrefixLabel(position, new GUIContent(nameString));
13.       if (GUI.Button(btnPos, valueString))
14.          property.boolValue = !value;
15.    }
16. }

At first it worked fine - I dropped DLL in Editor folder and my button was drawn.
Then at some point I included reference to GUILayout class instead of GUI. I started getting 2 errors.

I reverted changes to the code above, yet the error still happens whenever DLL is in project.

When I delete it, and place the exact same code as a script, it works properly. However starts failing when I drop DLL again - even when I comment out the attributes so the Drawers are not used - DLL just needs to be in the project. Errors stop when there's no more CustomPropertyDrawer attribute used in the library code - all else fails - even if the property drawer has no OnGUI overriden.


Adding a script in Unity itself as a wrapper

Code (csharp):

1. [CustomPropertyDrawer(typeof(ToggleButtonAttribute))]
2. public class ToggleButtonWrapper : ToggleButtonAttributeDrawer { }

seems to make issue go away, however I find it unnecessary hassle and hope there's a way to make it work directly from DLL.

 

Yes, I'll try to strip the project down a bit soon so it's smaller and less messy and then send you the files.

 

First of all, sorry for (very) late reply now. I got really busy with other things.
I copied project folder and started deleting things today - however, I noticed there's no error now. I checked the main, unstripped project too, restarted editor as well, and there's no error.
Should I send the smaller one with deleted things anyway for more investigation? I will keep eye out for the same issue happening again and will send asap then, can't promise how fast will this happen, though.