What is wrong with the chemical formula copper chloride?

The problem with your question is that "Copper chloride" is not a chemical formula; it is the name of a chemical compound. However, I understand what you are asking. The problem with the name "copper chloride" is that it is ambiguous. One must be able to write an unambiguous chemical formula from the compound's name and vice versa, but that cannot be done here since "copper chloride" can be either CuCl or CuCl2.

Oxidized copper exists either as Cu+1 or as Cu+2. In other Words, the copper atom has lost either one or two electrons. "Chloride" is chlorine with a -1 formal charge, thus it takes either one or two chloride ions to create [the neutral compound] copper chloride.

For metal ions, the name of the ion with the highest oxidation state has the suffix "-ic" and the ion with the lower oxidation state possesses the suffix "-ous." That means that copper chloride is actually either cupric chloride, CuCl2, or it is cuprous chloride, or CuCl.