The Hungarian MEK catalog (a PHP backend) returns a valid Atom feed
followed by trailing junk after </feed> — a stray PHP warning, an extra
tag, or text. Chrome's DOMParser ignores it, but Firefox's strict parser
fails with "junk after document element" and replaces the whole document
with a <parsererror>. The reader then sees a non-feed root, treats the
response as HTML, finds no OPDS link, and silently navigates back, so
browsing the catalog on Firefox web is broken on nearly every subpage.
Add parseOPDSXML(): on a parser error, re-parse the slice from the root
element's start tag to its last matching end tag, dropping any leading
prolog and trailing junk. If recovery still fails the original error
document is returned, so callers fall through to their existing
HTML/non-OPDS handling. Wire it into the three OPDS XML parse sites:
the reader (page.tsx), validateOPDSURL (adding a catalog), and the
subscription/auto-download feed checker. feedChecker also switches its
text.startsWith('<') detection to looksLikeXMLContent so the MEK feed's
leading newlines (no <?xml?> declaration, #4181) are recognized.
jsdom mirrors Firefox's strict behavior (same parsererror namespace), so
the regression tests run in the normal unit suite.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Huang Xin
1eaf16ffc2