api fixes for list filters

cmd/dev/sravnicli/products.go

@@ -9,6 +9,7 @@ import (
 
 	"git.loyso.art/frx/kurious/internal/common/client/sravni"
 	"git.loyso.art/frx/kurious/internal/common/errors"
+	"git.loyso.art/frx/kurious/internal/common/xslice"
 
 	"github.com/teris-io/cli"
 )
@@ -184,7 +185,13 @@ func (a *productsFilterCountAction) parse(args []string, options map[string]stri
 		return errors.SimpleError(learningTypeOptName + " is empty")
 	}
 
-	a.params.courseThematic = strings.Split(options[courseThematicOptName], ",")
+	filterNotEmpty := func(value string) bool {
+		return value != ""
+	}
+	a.params.courseThematic = xslice.Filter(
+		strings.Split(options[courseThematicOptName], ","),
+		filterNotEmpty,
+	)
 	a.params.learningSelectionType = options[learningTypeSelectionOptName]
 
 	client, err := makeSravniClient(a.ctx, a.log, options)