[Backport 2.x] fix explorer stats function typing crash #1027

Job	Run time
Run test group of app_analytics_test	17m 9s
Run test group of datasources_test	12m 25s
Run test group of event_analytics_test	23m 13s
Run test group of integrations_test	12m 13s
Run test group of metrics_analytics_test	11m 36s
Run test group of notebooks_test	14m 8s
Run test group of panels_test	18m 59s
Run test group of trace_analytics_test	27m 34s
	2h 17m 17s

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