fix: new linting errors

internal/handler/dashboard.go

@@ -8,6 +8,7 @@ import (
 	"spend-sparrow/internal/service"
 	"spend-sparrow/internal/template/dashboard"
 	"spend-sparrow/internal/utils"
+	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -74,14 +75,17 @@ func (handler DashboardImpl) handleDashboardMainChart() http.HandlerFunc {
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(http.StatusOK)
 
-		account := ""
-		savings := ""
+		accountBuilder := strings.Builder{}
+		savingsBuilder := strings.Builder{}
 
 		for _, entry := range series {
-			account += fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100)
-			savings += fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Savings)/100)
+			accountBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100))
+			savingsBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Savings)/100))
 		}
 
+		account := accountBuilder.String()
+		savings := savingsBuilder.String()
+
 		account = account[:len(account)-1]
 		savings = savings[:len(savings)-1]
 
@@ -137,23 +141,24 @@ func (handler DashboardImpl) handleDashboardTreasureChests() http.HandlerFunc {
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(http.StatusOK)
 
-		data := ""
+		dataBuilder := strings.Builder{}
 
 		for _, item := range treeList {
-			children := ""
+			childrenBuilder := strings.Builder{}
 
 			for _, child := range item.Children {
 				if child.Value < 0 {
-					children += fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, -child.Value)
+					childrenBuilder.WriteString(fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, -child.Value))
 				} else {
-					children += fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, child.Value)
+					childrenBuilder.WriteString(fmt.Sprintf(`{"name":"%s\n%.2f €","value":%d},`, child.Name, float64(child.Value)/100, child.Value))
 				}
 			}
 
+			children := childrenBuilder.String()
 			children = children[:len(children)-1]
-			data += fmt.Sprintf(`{"name":"%s","children":[%s]},`, item.Name, children)
+			dataBuilder.WriteString(fmt.Sprintf(`{"name":"%s","children":[%s]},`, item.Name, children))
 		}
-
+		data := dataBuilder.String()
 		data = data[:len(data)-1]
 
 		_, err = fmt.Fprintf(w, `
@@ -204,12 +209,14 @@ func (handler DashboardImpl) handleDashboardTreasureChest() http.HandlerFunc {
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(http.StatusOK)
 
-		value := ""
+		valueBuilder := strings.Builder{}
 
 		for _, entry := range series {
-			value += fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100)
+			valueBuilder.WriteString(fmt.Sprintf(`["%s",%.2f],`, entry.Day.Format(time.RFC3339), float64(entry.Value)/100))
 		}
 
+		value := valueBuilder.String()
+
 		if len(value) > 0 {
 			value = value[:len(value)-1]
 		}