It’s something new, we just introduced the plugin into our installation (we have other plugins and they all work), but then the site gives a 5xx error, and when I check the logs, I see what I sent you. My Dockerfile looks something like this:
FROM discourse/discourse:3.5.2
WORKDIR /var/www/discourse
# Install discourse-amazon-sns plugin
RUN git clone https://github.com/discourse/discourse-amazon-sns.git /var/www/discourse/plugins/discourse-amazon-sns && \
chown -R discourse:discourse /var/www/discourse/plugins/discourse-amazon-sns
EXPOSE 80