parseCachedEditorConfig caught only ENOENT, so an oversized path segment
(e.g. a 2KiB garbage string emitted by a hallucinating model) blew up
the renderer with an uncaught ENAMETOOLONG from fs.readFileSync. The
editorconfig probe is best-effort — there is no useful difference
between 'file missing' and 'open() refused for any other reason' from
the renderer's perspective. Catch every error, cache the miss so we do
not re-probe the same bogus path on every redraw, and add a regression
test that exercises the 2KiB-segment path through getIndentation.
Fixes#1871
roboomp
72f41f333e