Generic "Error creating alias" when attempting to create alias that already exists

[aaronraimist]

Could be a bit more friendly and say that the alias is already assigned to another room, or really friendly and offer to move it over to the new room if you were the one that created the original alias

[turt2live]

Thank you for reporting (it helps track all the things that went wrong). This is a duplicate of #9367 - I'll flag that accordingly.