validation for user input

src/download/download.py

@@ -128,7 +128,16 @@ def print_webcomics(webcomics: Dict[str, Dict]) -> int:
     for index, entry in enumerate(webcomics["webcomics"]):
         print(list_lines(index, entry["name"]))
 
-    return int(input("Select a webcomic: "))
+    max_index = len(webcomics["webcomics"]) - 1
+    while True:
+        raw = input("Select a webcomic: ").strip()
+        if not raw.isdigit():
+            print("Please enter a number.")
+            continue
+        choice = int(raw)
+        if 0 <= choice <= max_index:
+            return choice
+        print(f"Please enter a number between 0 and {max_index}.")
 
 
 def webcomic_manager():