gh-69714: Move the validation to the beginning of the function

No need to process the function.
This also helps in supporting CLI testing.

Author: bxsx

Lib/calendar.py

@@ -724,6 +724,9 @@ def main(args=None):
     locale = options.locale, options.encoding
 
     if options.type == "html":
+        if options.month:
+            parser.error("incorrect number of arguments")
+            sys.exit(1)
         if options.locale:
             cal = LocaleHTMLCalendar(locale=locale)
         else:
@@ -735,11 +738,8 @@ def main(args=None):
         write = sys.stdout.buffer.write
         if options.year is None:
             write(cal.formatyearpage(datetime.date.today().year, **optdict))
-        elif options.month is None:
-            write(cal.formatyearpage(options.year, **optdict))
         else:
-            parser.error("incorrect number of arguments")
-            sys.exit(1)
+            write(cal.formatyearpage(options.year, **optdict))
     else:
         if options.locale:
             cal = LocaleTextCalendar(locale=locale)