The bug seems to have been introduce in Pharo7.0-SNAPSHOT.build.102.sha.3f660fc.arch.64bit by merging the pull request https://github.com/pharo-project/pharo/pull/1847

On Wed, Jan 16, 2019 at 1:32 AM Hilaire via Pharo-users <pharo-users@lists.pharo.org> wrote:
Indeed, seems to only happen in a subclass of BlEement.

Hilaire

Le 15/01/2019 �� 21:33, Andrei Chis a ��crit��:
> It happens if you create methods in a class having a superclass with
> traits. For example if you create a subclass of BlElement you will get
> this error.
>
> What class are you editing when you get this errror?
>
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