fix: handle duplicate input

internal/services/auth/login_as_user.go

@@ -7,8 +7,8 @@ import (
 	"github.com/ardeman/project-legalgo-go/internal/utilities/utils"
 )
 
-func (sv *AuthSvc) LoginAsUser(spec authdomain.LoginReq) (string, error) {
-	user, err := sv.userRepo.GetUserByEmail(spec.Email)
+func (a *AuthSvc) LoginAsUser(spec authdomain.LoginReq) (string, error) {
+	user, err := a.userRepo.GetUserByEmail(spec.Email)
 	if err != nil {
 		return "", errors.New(err.Error())
 	}

internal/services/auth/register_staff.go

@@ -9,6 +9,10 @@ import (
 )
 
 func (a *AuthSvc) RegisterStaff(spec authdomain.RegisterStaffReq) (string, error) {
+	_, err := a.staffRepo.GetStaffByEmail(spec.Email)
+	if err == nil {
+		return "", errors.New("this email address is already in use")
+	}
 	hashedPwd, err := HashPassword(spec.Password)
 	if err != nil {
 		return "", err

internal/services/auth/register_user.go

@@ -9,6 +9,12 @@ import (
 )
 
 func (a *AuthSvc) RegisterUser(spec authdomain.RegisterUserReq) (string, error) {
+	_, err := a.userRepo.GetUserByEmail(spec.Email)
+
+	if err == nil {
+		return "", errors.New("this email address is already in use")
+	}
+
 	subsId, err := a.subsRepo.Create(spec.SubscribePlanID)
 	if err != nil {
 		return "", nil