It is very unlikely that you gave away compromising information. Your active logins, cookies, search history and the content of your visited websites are safe. Presumably, the most relevant sensitive information in your case is the last visited URL (which you had to explicitly agree to submit).
Also note that Firefox doesn't submit crash reports without your consent. In the Mozilla docs you can find details on how the Mozilla Crash Reporter works and how you can understand crash reports.
What does a crash report contain?
A Firefox crash report contains information relevant for debugging such as:
- Browser version
- Installed extensions
- Operating system version and configuration
- Stack trace of the crash (involved modules, functions, etc.)
You can optionally include the URL of where the crash has occurred and a contact email address.
Where can I view my previous crash reports?
You can view your crashes from inside Firefox at
about:crashes or locally at
~/.mozilla/firefox/Crash Reports/. All submitted Firefox crash reports are published on crash-stats.
Who else can view a crash report?
Everyone is able to view a basic version of your report but only few users can see sensitive details.
Some fields, such as "URL" and "Email Address", are privacy-sensitive and are only visible to users with minidump access.
So even if you submitted the URL - it's not public, developers will probably never read it given the total amount of crash reports, and nobody will know it was you.