allow claling Unassociate() on previously not initialized wxMimeTypesManager

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39780 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/unix/mimetype.cpp

@@ -2643,6 +2643,8 @@ size_t wxMimeTypesManagerImpl::EnumAllFileTypes(wxArrayString& mimetypes)
 
 bool wxMimeTypesManagerImpl::Unassociate(wxFileType *ft)
 {
+    InitIfNeeded();
+
     wxArrayString sMimeTypes;
     ft->GetMimeTypes(sMimeTypes);