LoginHelper.requestReauth() returns without a `telemetryEvent` when it gives up because a primary password prompt is already open. Two of its callers destructure that value unconditionally and throw a TypeError instead of exporting the passwords, in about:logins and in the contextual password manager. Move the recording into LoginHelper next to requestReauth(), where it can skip the missing event, and use it from both callers. No test: reproducing this needs a second primary password prompt to be open at the moment the export is started. Differential Revision: https://phabricator.services.mozilla.com/D324587