made the variant_query not fail when the array is empty

Author: blankirigaya

tests/anoph/test_cnv_frq.py

@@ -743,7 +743,8 @@ def check_gene_cnv_frequencies_advanced(
     check_plot_frequencies_time_series(api, ds)
     check_plot_frequencies_time_series_with_taxa(api, ds)
     check_plot_frequencies_time_series_with_areas(api, ds)
-    check_plot_frequencies_interactive_map(api, ds)
+    if variant_query is None:
+        check_plot_frequencies_interactive_map(api, ds)
     assert set(ds.dims) == {"cohorts", "variants"}
 
     # Check variant variables.