add-zip: fix error message for invalid files

cogs/emote.py

@@ -235,9 +235,11 @@ class Emotes(commands.Cog):
 		"""Try to add an emote from bytes. On error, return a string that should be sent to the user."""
 		try:
 			emote = await self.create_emote_from_bytes(guild, name, author_id, image_data, reason=reason)
+		except discord.InvalidArgument:
+			return discord.utils.escape_mentions(f'{name}: The file supplied was not a valid GIF, PNG, or JPEG file.')
 		except discord.HTTPException as ex:
-			return (
-				'An error occurred while creating the emote:\n'
+			return discord.utils.escape_mentions(
+				f'{name}: An error occurred while creating the the emote:\n'
 				+ utils.format_http_exception(ex))
 		return f'Emote {emote} successfully created.'
 

utils/errors.py

@@ -45,7 +45,7 @@ class InvalidFileError(EmoteManagerError):
 class InvalidImageError(InvalidFileError):
 	"""The image is not a GIF, PNG, or JPG"""
 	def __init__(self):
-		super().__init__('The image supplied was not a GIF, PNG, or JPG.')
+		super(Exception, self).__init__('The image supplied was not a GIF, PNG, or JPG.')
 
 class PermissionDeniedError(EmoteManagerError):
 	"""Raised when a user tries to modify an emote without the Manage Emojis permission"""

utils/image.py

@@ -68,13 +68,10 @@ def scale_resolution(old_res, new_res):
 def mime_type_for_image(data):
 	if data.startswith(b'\x89PNG\r\n\x1a\n'):
 		return 'image/png'
-	elif data.startswith(b'\xFF\xD8') and data.rstrip(b'\0').endswith(b'\xFF\xD9'):
+	if data.startswith(b'\xFF\xD8') and data.rstrip(b'\0').endswith(b'\xFF\xD9'):
 		return 'image/jpeg'
-	elif data.startswith((b'GIF87a', b'GIF89a')):
+	if data.startswith((b'GIF87a', b'GIF89a')):
 		return 'image/gif'
-	elif data.startswith(b'RIFF') and data[8:12] == b'WEBP':
-		return 'image/webp'
-	else:
 	raise errors.InvalidImageError
 
 def image_to_base64_url(data):