[FIX] plugin tracker: validate undefined variable.
From Glitchtip there is a notice about the undefined variable while trying to add informations on tracker, because of the scope limitation of these variables, which means that when we want to use them we have a notice. So the solution is to declare them before they are used. Task related: https://avan.tech/item68774-Fix-all-errors-in-logs-that-are-not-related-to-Cypht-Webmail-Smarty-icons-and-menus-was-Use-the-GlitchTip-error-reporting-as-a-perpetual-to-do-list-for-junior-developers Glitchtip link issues: https://app.glitchtip.com/evoludata/issues/1891086 https://app.glitchtip.com/evoludata/issues/1891085 https://app.glitchtip.com/evoludata/issues/1891084 https://app.glitchtip.com/evoludata/issues/1891083 https://app.glitchtip.com/evoludata/issues/1891082 https://app.glitchtip.com/evoludata/issues/1891081 https://app.glitchtip.com/evoludata/issues/1891080 https://app.glitchtip.com/evoludata/issues/1891079