Solved a bug where users could change their e-mail to another user's email

src/constants/errors.ts

@@ -1,4 +1,4 @@
-export type Error = "E001" | "E002";
+export type Error = "E001" | "E002" | "E003";
 export interface ErrorMessage {
 	error: Error;
 	message: string;
@@ -7,4 +7,5 @@ export interface ErrorMessage {
 export const errorMessages: {[key in Error]: string} = {
 	E001: "Wrong password!",
 	E002: "Invalid e-mail",
+	E003: "E-mail already in use!",
 };