I used npx storybook@next upgrade --prerelease and adjust preview.js and main.js manuell based on the migration guide. storybook dev gives now the following error:
TypeError: Cannot use 'in' operator to search for 'CallExpression' in undefined at explode (/var/www/node_modules/@storybook/csf-tools/dist/index.js:6:8352)
It seems that in gets called on an undefined object. Do you know how to fix this? Thanks a lot.