 class WeakR8b7c:f320:99b9:690f:4595:cd17:293a:c069RefError 

Parent:
StandardError
  RefError is raised when a referenced object has been recycled by the garbage collector  

    Ruby Core © 1993–2017 Yukihiro MatsumotoLicensed under the Ruby License.Ruby Standard Library 
{'path': 'public/docs/ruby~2.6/weakref/referror.html', 'source': 'DevDocs.IO'}