Minor comment adjustemnts

src/main.py

@@ -3,22 +3,17 @@ import image_processing
 
 import os, sys, time
 
-####
-# CURRENT ISSUES
-####
-#
-# Pixelfed API doesn't honour newlines. - Possibly look at HTML formatting?
-# Pixelfed publishing is missing date - Needs parsing and appending to description
-
-
 def main():
     if len(sys.argv) < 2:
-        print("Usage: social-photos <directory_or_file_path>")
+        print("Usage: social-photos <directory_or_file_path>", file=sys.stderr)
+        sys.exit(1)
     else:
         path = sys.argv[1]
 
+        # Check whether path points to a file or a directory.  If neither, exit.
+        
         if not os.path.exists(path):
-            print(f"'{path}' does not exist.")
+            print(f"'{path}' does not exist.", file=sys.stderr)
             sys.exit(1)
         elif os.path.isfile(path):
             print(f"'{path}' is a file.")
@@ -27,7 +22,7 @@ def main():
             print(f"'{path}' is a directory.")
             files = list_files_in_directory(path)
         else:
-            print(f"'{path}' is neither a file nor a directory.")
+            print(f"'{path}' is neither a file nor a directory.", file=sys.stderr)
             sys.exit(1)
         
         print("These files will be uploaded:")