If you enable error reporting you help us greatly in improving SkyTemple!
We solely collect this data for the purposes of error reporting and anonymous usage statistics.
The data is sent to sentry.io for analysis. You can find an example error report here. The error report also contains logs and information about the application state and some basic information about your system, these are not shown in the link, but you can view a preview of that here. Additionally you can look at the source code of the module that collects the data.