Fix error with query string
Fix error with query string

When the text area was emptied, it would still
pass the string on as Just "", which would result
in "query=" being added to the url.

Aloomaio/alertmanager,tyrken/alertmanager,GoogleCloudPlatform/alertmanager,prometheus/alertmanager,tinytub/alertmanager,prometheus/alertmanager,joehandzik/alertmanager,Kellel/alertmanager,tyrken/alertmanager,joehandzik/alertmanager,Aloomaio/alertmanager,tyrken/alertmanager,GoogleCloudPlatform/alertmanager,GoogleCloudPlatform/alertmanager,tinytub/alertmanager,tinytub/alertmanager,prometheus/alertmanager,stuartnelson3/am-ui,Aloomaio/alertmanager,GoogleCloudPlatform/alertmanager,joehandzik/alertmanager,Kellel/alertmanager,stuartnelson3/am-ui,tyrken/alertmanager,prometheus/alertmanager,Kellel/alertmanager