debug-ignored-errors is a variable defined in `C source code'.
Its value is

("^Version control package .*.el not found. Use vc.el instead$" "^There is no file to merge$" "^Merge of directory revisions aborted$" "^Directory merge aborted$" "^Directories . and . are the same: " "^Buffer .* doesn't exist$" "^File `.*' is a directory$" "^File `.*' does not exist or is not readable$" "^Can't determine display width.$" "^Failed to retrieve revision: $" "^Current buffer is not visiting any file$" "^All right. Make up your mind and come back...$" "^You forgot to specify a region in buffer " "^Output from `diff' not found$" "^Buffer out of sync for file " "^Buffer is out of sync for file " "^Nothing saved for diff .* in buffer " "^At beginning of the difference list$" "^At end of the difference list$" "^This command makes sense only when merging with an ancestor$" "Emacs is not running as a window application$" "^Don't know how to toggle read-only in buffer " "^Not merging with ancestor$" "^Lost connection to ancestor buffer...sorry$" "^No fine differences in this mode$" "^Recomputation of differences cancelled$" "^Patch appears to have failed$" "^`.*' is not an ordinary file$" "^No session info in this line$" "^No active Ediff sessions or corrupted session registry$" "^This Ediff session is not part of a session group$" "^Aborted$" "^The patch buffer wasn't found$" "^Can't make context diff for Session $" "^Ediff: something wrong--no multiple diffs buffer$" "^Can't hide active session, $" "^This session group has no parent$" "^This command is inapplicable in the present context$" "^Lost difference info on these directories$" "^ediff-shrink-window-C can be used only for merging jobs$" ": Invalid op in ediff-check-version$" ": This command runs in Ediff Control Buffer only!$" "^Undocumented command! Type `G' in Ediff Control Panel to drop a note to the Ediff maintainer$" "^Hmm... I don't see an Ediff command around here...$" "^Errors in diff output. Diff output is in " search-failed "^Invalid face:? " "^No word found to check!$" beginning-of-line beginning-of-buffer end-of-line end-of-buffer end-of-file buffer-read-only file-supersession user-error)

Original value was
(beginning-of-line beginning-of-buffer end-of-line end-of-buffer end-of-file buffer-read-only file-supersession user-error)

List of errors for which the debugger should not be called.
Each element may be a condition-name or a regexp that matches error messages.
If any element applies to a given error, that error skips the debugger
and just returns to top level.
This overrides the variable `debug-on-error'.
It does not apply to errors handled by `condition-case'.

You can customize this variable.