Print error instead of exception in fetch_details

[rascasoft]

This commit converts the raise exception statement inside the
fetch_details function into a print statement, so that when
working on multi entries (and just some fails) the others can be
processed in any case.

[pe-st]

Hello @rascasoft, sorry for the late feedback. Would a command line option to select your desired behaviour also work? I personally prefer a fail-fast approach in this case, if this problem happens I'd assume a temporary issue with Garmin Connect and I'd want to know that my download is incomplete. If it's just mentioned in a log I'd probably miss it, so I personally prefer the exception behaviour

[rascasoft]

Actually @pe-st it's been a very long time since I did this, and so whatever fits you is OK by me ;)