5.4p2 ​​get_skinIndex is not allowed be called from a ScriptableObject constructor

get_skinIndex is not allowed to be called from a ScriptableObject constructor (or instance field initializer), call it in OnEnable instead. Called from ScriptableObject 'SFN_Append'.

i've been seeing a lot of these errors in all kinds of extensions since 5.4, not just shaderforge.