Fix: open correct month for newsletter editing

Related to #18 (closed)

src/components/Newsletter/Newsletter.tsx

@@ -30,14 +30,18 @@ export type ContentItems =
   | ''
 
 const Newsletter: React.FC = () => {
-  // Functional rule :
-  // Display next month after the 3rd of the current month
+  /**
+   * Display previous month until the newsletter is sent on the 3rd day of the month
+   */
   const getCurrentNewsletterDate = (): Date => {
-    const newsletterDate = new Date()
-    if (newsletterDate.getDate() >= 3) {
-      newsletterDate.setMonth(newsletterDate.getMonth() + 1)
-    }
-    return newsletterDate
+    const today = new Date()
+    const currentDay = today.getDate()
+    const currentMonth = today.getMonth()
+    const currentYear = today.getFullYear()
+
+    return currentDay < 3
+      ? new Date(currentYear, currentMonth, 1)
+      : new Date(currentYear, currentMonth + 1, 1)
   }
 
   const [date, setDate] = useState<Date>(getCurrentNewsletterDate())