a98637c153
useTheme() on line 32 returns null so I tested this change to the import on my local copy, which gets the sonar plugin working. Other plugins seem to be importing from '@material-ui/core', e.g. https://github.com/backstage/backstage/blob/7ee15d2c5b40a8984aacabe7bdf5ccab759d95a6/plugins/catalog/src/components/CatalogFilter/AllServicesCount.tsx#L19
Plugins
Backstage is a single-page application composed of a set of plugins. This folder holds numerous plugins that are managed by this repository.
For more information about the plugin ecosystem, see the documentation here:
You can also see the Plugin Marketplace for other open source plugins you can add to your Backstage instance.
Suggesting a plugin
If you start developing a plugin that you aim to release as open source, we suggest that you create a new Issue. This helps the community know what plugins are in development.
You can also use this process if you have an idea for a good plugin but you hope that someone else will pick up the work.