Added errors for services

internal/application/errors/already_exists_error.go

@@ -0,0 +1,15 @@
+package errors
+
+type AlreadyExistsError struct {
+	msg string
+}
+
+func NewAlreadyExistsError(msg string) *AlreadyExistsError {
+	return &AlreadyExistsError{
+		msg: msg,
+	}
+}
+
+func (e *AlreadyExistsError) Error() string {
+	return "Already exists: " + e.msg
+}

internal/application/errors/db_error.go

@@ -4,12 +4,12 @@ type DBError struct {
 	msg string
 }
 
-func NewDBError(msg string) DBError {
-	return DBError{
+func NewDBError(msg string) *DBError {
+	return &DBError{
 		msg: msg,
 	}
 }
 
 func (e *DBError) Error() string {
-	return e.msg
+	return "Database error:" + e.msg
 }

internal/application/errors/not_found_error.go

@@ -11,5 +11,5 @@ func NewNotFoundError(msg string) *NotFoundError {
 }
 
 func (e *NotFoundError) Error() string {
-	return e.msg
+	return "Not found error: " + e.msg
 }

internal/application/errors/validation_error.go

@@ -0,0 +1,15 @@
+package errors
+
+type ValidationError struct {
+	msg string
+}
+
+func NewValidationError(msg string) *ValidationError {
+	return &ValidationError{
+		msg: msg,
+	}
+}
+
+func (e *ValidationError) Error() string {
+	return "Validation error: " + e.msg
+}