Issue Board URLs without filters have an unwanted `?=` at the end
Upon visiting any issue board URL, like https://gitlab.com/gitlab-org/omnibus-gitlab/boards/289804 , a ?=
gets appended to the URL. As per my understanding, it is used to specify GET parameters so as to filter the issues based on author, milestone etc. For non-filtered scenarios, which is the default when we navigate to the issue board from sidebar, we should not be adding them.
We probably missed to add a check for nulls before generating the URL.
/cc @smcgivern