Re-add "type" alias for data_type parameter

Migrate rest of app skeleton from flask to fastapi

Handle empty buffer returned from Edge

ObsPy's waveserver.py (and associated methods) do not handle an empty
buffer returned from Edge's earthworm server. In short, they generate
a None value instead of an empty byte string as one might expect (and
they clearly did expect, since they attempted `len(dat)` where dat
was expected to be a byte string, but was a None object if/when Edge
had no data. This fix employs a try/except clause to generate an
empty string if the waveserver client fails with a TypeError, as is
the case when Edge returns an empty buffer.

Parse fix