Update path validation error handling

server/internal/storage/errors.go

@@ -0,0 +1,24 @@
+// storage/errors.go
+
+package storage
+
+import (
+	"errors"
+	"fmt"
+)
+
+// PathValidationError represents a path validation error (e.g., path traversal attempt)
+type PathValidationError struct {
+	Path    string
+	Message string
+}
+
+func (e *PathValidationError) Error() string {
+	return fmt.Sprintf("%s: %s", e.Message, e.Path)
+}
+
+// IsPathValidationError checks if the error is a PathValidationError
+func IsPathValidationError(err error) bool {
+	var pathErr *PathValidationError
+	return err != nil && errors.As(err, &pathErr)
+}