find_chandra_obsid behaviour when there's no coverage

[DougBurke]

Why am I seeing this error message:

% find_chandra_obsid "a2472" v=4
Running: find_chandra_obsid
  version: 06 January 2023
Querying name resolvers for name=a2472
Found ra=340.47375 dec=17.54166667
    = 22h 41m 53.69999999999294s 17d 32' 30.000012000005256"
Querying Chandra archive for ra=340.47375 dec=17.54166667 radius=0.016666666666666666 inst=all grat=all
Retrieving URL: https://cxcfps.cfa.harvard.edu/cgi-bin/cda/footprint/get_vo_table.pl?strict=1&POS=340.47375,17.54166667&SIZE=0.016666666666666666 timeout=None
Search returned 0 rows
Chandra search found 0 results
After removing duplicates, have 0 matches
# find_chandra_obsid (06 January 2023): ERROR max() arg is an empty sequence

It should error out better than this. What has changed?