When the user views a Data:.chart page, they currently see a tabular representation of the chart definition JSON. Instead, they should see a rendering of the chart, using the default data source specified in the chart definition.
Sometimes it won't be possible to render a chart preview, for example if the definition is invalid or if the data source is missing. In that case we should display an error box explaining that.
The JsonConfig extension allows for custom page view behavior, see https://www.mediawiki.org/wiki/Extension:JsonConfig#Customizing_behavior_on_the_storage_wiki
- Viewing a valid Data:.chart page displays the chart
- Viewing an invalid Data:.chart page displays an error message (ideally explaining the type of issue e.g. invalid type, missing parameter, etc; but that's not needed)
- Viewing a Data:.chart page that has no default data source but is otherwise valid displays a warning message