fix no error popup shown if a signup user wants to be in a team with themselves

src/actions/signup.ts

@@ -32,7 +32,7 @@ export const signup = {
       // check if username and team member is equal
       if (input.username.toLowerCase() === input.teamMember.toLowerCase()) {
         throw new ActionError({
-          code: 'BAD_REQUEST',
+          code: 'CONFLICT',
           message: 'Du kannst nicht mit dir selber in einem Team sein'
         });
       }