NullReference on textfield

Hello community,

I’ve encountered a very troublesome error recently, happens every time I edit a textfield… the textfield being in a window.
Many people have this issue when not initializing the string for the textfield, mine is initialized… any ideas ?

NullReferenceException: Object reference not set to an instance of an object
UnityEngine.GUI.DoTextField (Rect position, Int32 id, UnityEngine.GUIContent content, Boolean multiline, Int32 maxLength, UnityEngine.GUIStyle style) (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/GUI.cs:601)
UnityEngine.GUI.TextArea (Rect position, System.String text) (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/GUI.cs:453)
RenameProjectPopUp.DrawChild () (at Assets/NewUI/menuAvril/RenameProjectPopUp.cs:15)
IRCPopUp.doWindow (Int32 WindowID) (at Assets/NewUI/IRCPopUp.cs:253)
UnityEngine.GUI.CallWindowDelegate (UnityEngine.WindowFunction func, Int32 id, UnityEngine.GUISkin _skin, Int32 forceRect, Single width, Single height, UnityEngine.GUIStyle style) (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/GUI.cs:1283)

Okay, found it.
I somehow modified the unity’s default skin, and it had a problem with the font, causing the exception.