isDisallowed() returns true for / despite no matching Disallow rule in robots.txt

[seveun]

Hi,

I'm encountering a possible issue with the way isDisallowed() behaves when parsing the robots.txt file from https://www.natureetdecouvertes.com/robots.txt.

Context
I'm checking if crawling the homepage / is allowed for a standard browser User-Agent like:

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Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36
When I run:

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const isAllowed = robotsTxt.isAllowed('https://www.natureetdecouvertes.com/', userAgent);
const isDisallowed = robotsTxt.isDisallowed('https://www.natureetdecouvertes.com/', userAgent);
I get:

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isAllowed === undefined
isDisallowed === true
However, the robots.txt does not contain any rule explicitly disallowing /. There is no Disallow: /, and the default behavior according to the Robots Exclusion Protocol (RFC 9309) is to allow access to / unless explicitly blocked.

Expected behavior
isDisallowed('/') should return false, and isAllowed('/') should return true (or at least not undefined if a fallback to User-agent: * applies).

Notes
The user-agent I’m testing is not listed in any specific User-agent: group, so the fallback to User-agent: * should apply.

There is no Disallow: / or any wildcard rule that matches only /.

Can you confirm if this is intended behavior? Otherwise, it seems like a parsing bug or fallback handling issue.

Thanks!