cmd/pkgserver: format get error messages

This improves source code readability on smaller displays.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/pkgserver/api.go

@@ -81,21 +81,33 @@ func (index *packageIndex) handleStatus(w http.ResponseWriter, r *http.Request)
 	}
 }
 
+// handleGet writes a slice of metadata with specified order.
 func (index *packageIndex) handleGet(w http.ResponseWriter, r *http.Request) {
 	q := r.URL.Query()
 	limit, err := strconv.Atoi(q.Get("limit"))
 	if err != nil || limit > 100 || limit < 1 {
-		http.Error(w, fmt.Sprintf("limit must be an integer between 1 and 100"), http.StatusBadRequest)
+		http.Error(
+			w, "limit must be an integer between 1 and 100",
+			http.StatusBadRequest,
+		)
 		return
 	}
 	i, err := strconv.Atoi(q.Get("index"))
 	if err != nil || i >= len(index.sorts[0]) || i < 0 {
-		http.Error(w, fmt.Sprintf("index must be an integer between 0 and %d", len(index.sorts[0])-1), http.StatusBadRequest)
+		http.Error(
+			w, "index must be an integer between 0 and "+
+				strconv.Itoa(int(rosa.PresetUnexportedStart-1)),
+			http.StatusBadRequest,
+		)
 		return
 	}
 	sort, err := strconv.Atoi(q.Get("sort"))
 	if err != nil || sort >= len(index.sorts) || sort < 0 {
-		http.Error(w, fmt.Sprintf("sort must be an integer between 0 and %d", len(index.sorts)-1), http.StatusBadRequest)
+		http.Error(
+			w, "sort must be an integer between 0 and "+
+				strconv.Itoa(sortOrderEnd),
+			http.StatusBadRequest,
+		)
 		return
 	}
 	values := index.sorts[sort][i:min(i+limit, len(index.sorts[sort]))]