By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Fix watch crash on attachment in nonexistent directory When an attachment's path points into a directory that does not exist (for example because of a typo), checkAttachment tried to list that directory with listDirRel to suggest similar filenames, which threw an uncaught IO exception (getDirectoryContents:openDirStream: does not exist). The watch loop only catches ExitCode, so this crashed the whole watch process. Wrap the directory listing in forgivingAbsence so a nonexistent parent directory simply yields no suggestions, and the normal CE_MISSING_ATTACHMENT error is reported instead.