Error reading cache: missing data

[tahini]

On one of our instances, we have this error message when starting the server:

info: [2023-08-31 12:20:38.516] [info] Fetching trips and connections from cache...(33.0%)

info: [2023-08-31 12:20:38.679] [info] Fetching trips and connections from cache...(45.0%)

info: [2023-08-31 12:20:38.785] [info] Fetching trips and connections from cache...(56.0%)

error: terminate called after throwing an instance of 'std::out_of_range'
  what():  map::at

Restarting the Transition instance, which recreated the cache, fixed the problem, but how did we get to this state? A more helpful error message would help debug what happened on the cache side

[greenscientist]

@tahini Did you keep a copy of the old data?