bugfix: Fix issue where edit fails if sub req fails

[damassi]

Addresses https://artsyproduct.atlassian.net/browse/GRO-147

Ran into an issue where this specific feature article would now accept edits, but others worked just fine. Digging in, it turns out that there was an error around an artist parsed from the body (or hyperlinked) being removed from gravity, with its ID returning 404, which would cause the entire edit to fail.

Since there's lots of automatic parsing and linking happening in Positron (and potentially many calls to grav for a given article), it would be better to gracefully fail, versus erroring out completely.

[codecov[bot]]

Codecov Report

Merging #2915 (53a1122) into master (b0b61a2) will decrease coverage by 0.0%. The diff coverage is 83.3%.

@@           Coverage Diff            @@
##           master   #2915     +/-   ##
========================================
- Coverage    83.4%   83.4%   -0.1%     
========================================
  Files         195     195             
  Lines        5390    5392      +2     
  Branches      998     998             
========================================
+ Hits         4497    4498      +1     
- Misses        638     639      +1     
  Partials      255     255             

[jonallured]

@damassi thanks for all the investigation that went into figuring this out!! 🙌