Raise a better error message if bids file is not found (generally raise better error message if file is not found)

[jdkent]

Is your feature request related to a problem? Please describe.
When files are not found, NiBetaSeries does not always raise a good error message, like when
a bold file in the original bids directory is not found this line

Describe the solution you'd like
Raise useful and actionable error message.

Describe alternatives you've considered
create a function/class that handles bids queries generally and raises good error messages

Additional context
N/A