When manticore isn't available or has been disabled/not loaded (like not available on debian yet) kolab_files generates a javascript error when opening the calendar.
```
ReferenceError: manticore_api is not defined
kolab_files.js:199:3
```
The code block in question looks like this:
```
function kolab_files_init()
{
[... lots of stuff ...]
manticore = new manticore_api(manticore_config);
};
```
I've just realized the core already looks a bit different due to WOPI integration, but in general: We can't call manticore_api isn't loaded/available