No possible route #119
Description
I'm getting a few errors that seem correlated:
- "No possible route"
- "Assertion failed: (> len1 len2)"
This happened while jumping between saved states with l and r, and i could no longer navigate forward to the most recent save with r. after this error, i also noticed the edit history was significantly smaller.
it seems this is a known occasional issue, but not explicitly tracked till now.
iiuc, it's caused by emacs garbage-collecting undo history while in the middle of a vundo command? if so, it seems very complicated to fix.
as a naive guess for a solution, could vundo--move-to-node let-bind undo-limit to a larger value to make gc interference less likely until it gets a chance to do its own cleanup? i expect there could be a few problems with that approach though.
one possible flaw with my suggestion. I don't know if the added "tail" nodes are proportional in size to the amount of text changed by an undone edit, or if they share that information with existing nodes (in which case each added node has a small and predictable size). if the former, it may be difficult to set a reasonable value that doesn't risk menory issues.