Bugzilla

This corner case is currently throwing from the call to `aBrowser.contentPrincipal.isThirdPartyPrincipal(aInstallingPrincipal)`, we should instead check explicitly if aInstallingPrincipal is a NullPrincipal and reject the request explicitly (so that we can also provide a better error message logged in the console to help the webapp developer to understand why the request has been rejected).

This corner case is currently throwing from the call to `aBrowser.contentPrincipal.isThirdPartyPrincipal(aInstallingPrincipal)`, we should instead check explicitly if aInstallingPrincipal is a NullPrincipal and reject the request explicitly (so that we can also provide a better error message logged in the console to help the webapp developer to understand why the request has been rejected).

STR (with already SitePermsAddonProvider enabled through pref):
- open a tab and load https://cdpn.io/k88hudson/fullpage/LYmBNGQ
- open the Browser Console and look for the rejection originated from AddonManager installSitePermsAddonFromWebpage method.

Expected behavior:
- An explicit reason for rejecting the request (e.g. "SitePermsAddons install is disallowed from sandboxed subframes")

This corner case is currently throwing from the call to `aBrowser.contentPrincipal.isThirdPartyPrincipal(aInstallingPrincipal)`, we should instead check explicitly if aInstallingPrincipal is a NullPrincipal and reject the request explicitly (so that we can also provide a better error message logged in the console to help the webapp developer to understand why the request has been rejected).

STR (with already SitePermsAddonProvider enabled through pref):
- open a tab and load https://cdpn.io/k88hudson/fullpage/LYmBNGQ
- open the Browser Console and look for the rejection originated from AddonManager installSitePermsAddonFromWebpage method.

Expected behavior:
- An explicit reason for rejecting the request (e.g. "SitePermsAddons install is disallowed from sandboxed subframes")

(and Bug 1792993 will improve how we surface that to webapp developers by making sure it is going to be visible in the DevTools webconsole panel associated to the tab that is triggering the error).