Fix product performance grouped JSON build

svc/routes/product_performance.go

@@ -273,6 +273,13 @@ func GetProductPerformanceGroupedHandler(pg *sql.DB) http.HandlerFunc {
 		groupLevels := splitCSVQuery(r.URL.Query().Get("group_levels"))
 		limit := intQuery(r, "limit", 50000)
 		expanded := map[string]bool{}
+		const maxExpandedGroupKeys = 200
+		addExpandedKey := func(key string) {
+			key = strings.TrimSpace(key)
+			if key != "" && len(expanded) < maxExpandedGroupKeys {
+				expanded[key] = true
+			}
+		}
 		if r.Method == http.MethodPost {
 			var body struct {
 				Mode         string   `json:"mode"`
@@ -298,17 +305,11 @@ func GetProductPerformanceGroupedHandler(pg *sql.DB) http.HandlerFunc {
 				limit = body.Limit
 			}
 			for _, key := range body.ExpandedKeys {
-				key = strings.TrimSpace(key)
-				if key != "" {
-					expanded[key] = true
-				}
+				addExpandedKey(key)
 			}
 		} else {
 			for _, key := range strings.Split(r.URL.Query().Get("expanded_keys"), ",") {
-				key = strings.TrimSpace(key)
-				if key != "" {
-					expanded[key] = true
-				}
+				addExpandedKey(key)
 			}
 		}