I cant find any mistake but my compiler says its a mistake

No

No

No

This is bad advice. Never use IEEE.std_logic_unsigned.all or IEEE.std_logic_signed.all. Those are non standard libraries, and cause a variety of problems, especially the day where you will need to use both signed and unsigned values in the same module.

Only use those two packages:

library IEEE;

use IEEE.std_logic_1164.all;

use IEEE.numeric_std.all;

Then change the type of the signal counter to wither "signed" or "unsigned", depending on what you want, and then you can just use

counter <= counter + 1;

If you never need the actual bit representation of the signal counter you can also make it a natural or an integer. Just remember to put a fixed range on it.