fix: instanceof MedusaError does not work (#9094)

* fix(error): add custom name

* revert: remove changeset

as requested https://github.com/medusajs/medusa/pull/9094#discussion_r1753971768

* refactor(error): use object identifier to check error type

packages/core/utils/src/common/errors.ts

@@ -29,6 +29,9 @@ export const MedusaErrorCodes = {
  * @extends Error
  */
 export class MedusaError extends Error {
+  // Symbol is not serializable
+  __isMedusaError = true
+
   public type: string
   public message: string
   public code?: string
@@ -55,4 +58,11 @@ export class MedusaError extends Error {
     this.message = message
     this.date = new Date()
   }
+
+  /**
+   * Checks the object for the MedusaError type.
+   */
+  static isMedusaError(error: any): error is MedusaError {
+    return !!error.__isMedusaError
+  }
 }