discord.py: custom reason without duty necessarily write them and error message if you don't specify the user - discord.py

Question

I've been programming with discord.py for 3 days and I'm a beginner, let's say ...
While trying to complete with all possible errors the mute command I noticed that I have to write a reason to execute the command (which I would like to be optional) and that when I don't specify the user the message "specify the user".
How can I solve it?
Here is the complete code
#mute
#client.command()
#commands.has_permissions(ban_members=True)
async def mute(ctx, member: discord.Member=None,*,arg):
role = get(member.guild.roles, id=int("691009285634654229"))
if not member:
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name="Per favore specifica l'utente!",
icon_url="'https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'"
)
await ctx.send(embed=embed)
return
if (ctx.author == member):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'Non puoi mutare te stesso!',
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)
return
if get(member.roles, name='Mutato'):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'{member.display_name} è attualmente mutato',
icon_url=f'{member.avatar_url}'
)
await ctx.send(embed=embed)
return
if get(member.roles, name='Moderatori'):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'Non puoi mutare un moderatore!',
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)
return
if get(member.roles, name='Presidente ad Interim del LMII'):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'Non puoi mutare un moderatore!',
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)
return
if get(member.roles, name='Co-Triumvirato'):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'Non puoi mutare un moderatore!',
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)
return
if get(member.roles, name='Triumvirato'):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name=f'Non puoi mutare un moderatore!',
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)
return
embed = discord.Embed(
color=discord.Colour.green()
)
embed.set_author(
name=f'{member.display_name} è stato mutato',
icon_url=f'{member.avatar_url}'
)
embed.set_footer(text=f'Motivo: {arg}')
await member.add_roles(role)
await ctx.send(embed=embed)
embed = discord.Embed(
color=discord.Colour.gold()
)
embed.set_author(
name=f'{ctx.author._user} ha mutato {member._user}',
icon_url=f'{member.avatar_url}'
)
embed.set_footer(text=f'Motivo: {arg}')
embed.add_field(
name='Utente mutato:',
value=f'{member._user}',
inline=True
)
embed.add_field(
name='Mutato da:',
value=f'{ctx.author._user}',
inline=True
)
embed.add_field(
name='Durata:',
value='∞',
inline=True
)
channel = client.get_channel(729553772547932190)
await channel.send(embed=embed)
#mute.error
async def mute_error(ctx, error):
if isinstance(error, commands.CheckFailure):
embed = discord.Embed(
color=discord.Colour.red()
)
embed.set_author(
name="Non ti è permesso mutare",
icon_url='https://cdn.discordapp.com/attachments/640563710104043530/730639329453670420/DuscePeppe_FRIULI.png'
)
await ctx.send(embed=embed)

Answer 1

In regards to the error message, if someone doesn't specify an argument (user) or a wrong/incorrect argument, you can use the following code.
#client.event
async def on_command_error(ctx, error):
if isinstance(error, commands.BadArgument):
embed=discord.Embed(title="Error", description="You haven't specified the correct arguments.", color=0xff0000)
await ctx.send(embed=embed)
elif isinstance(error, commands.UserNotFound):
embed=discord.Embed(title="Error", description="I could not find the user.", color=0xff0000)
await ctx.send(embed=embed)
elif isinstance(error, commands.MissingRequiredArgument):
embed=discord.Embed(title="Error", description="There are some arguments missing!", color=0xff0000)
await ctx.send(embed=embed)
else:
embed=discord.Embed(title="Error", description="An unknown error has occured, it has been logged on the bot console", color=0xff0000)
await ctx.send(embed=embed)
raise error