Default autoselect backend is confusing

[r2dliu]

The logic for autoselect backend is not terribly visible to the user and leads to confusing messaging.

In my case, I did not need bioformats but issues with the zarr path resulted in it autoswitching to bioformats and eventually spitting out errors about missing java related executables. Without the knowledge of digging into the source and finding the autoselect, I would not know that this error was not relevant to my use case, and that I did not actually need to install those (which I did know but only from reading the readme, not from library messaging)

Potentially it is better to simply throw an exception if the autoselect logic does not infer the data type from the path.

EDIT: actually what throws me off more is even if I explicitly define pass the backend in Reader constructor, the autoselect and override can still happen.