fix: decode params using json tags

pkg/sesamy/decode.go

@@ -0,0 +1,18 @@
+package sesamy
+
+import (
+	"github.com/mitchellh/mapstructure"
+)
+
+func Decode(input any, output any) error {
+	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
+		Result:               output,
+		TagName:              "json",
+		WeaklyTypedInput:     true,
+		IgnoreUntaggedFields: true,
+	})
+	if err != nil {
+		return err
+	}
+	return decoder.Decode(input)
+}

pkg/sesamy/event.go

@@ -1,9 +1,5 @@
 package sesamy
 
-import (
-	"github.com/mitchellh/mapstructure"
-)
-
 type Event[P any] struct {
 	// Reserved names: https://developers.google.com/analytics/devguides/collection/protocol/ga4/reference?client_type=gtag#reserved_names
 	Name EventName `json:"name"`
@@ -33,6 +29,10 @@ func (e Event[P]) AnyEvent() Event[any] {
 	}
 }
 
-func (e Event[P]) DecodeParams(output any) error {
-	return mapstructure.Decode(e, output)
+func (e Event[P]) Decode(output any) error {
+	return Decode(e, output)
+}
+
+func (e Event[P]) DecodeParams(output any) error {
+	return Decode(e.Params, output)
 }