SyntaxError: "undefined" is not valid JSON

[galaxyproject-sentryintegration]

This happens if a user attempts to edit a dataset with invalid id, or probably anything they don't have permission to access.
Example url: https://usegalaxy.org/datasets/f9cad7b01a4721359a227c867765c2d3/edit

We still render the rest of the form interface, which probably doesn't make sense.

Sentry Issue: GALAXY-MAIN-YBF

SyntaxError: "undefined" is not valid JSON
  at JSON.parse (<anonymous>)
...
(45 additional frame(s) were not displayed)

[davelopez]

Should be fixed in #18188