added errorCode mock

Signed-off-by: Pujal <[email protected]>

Author: pujal0909

packages/zowe-explorer/__tests__/__mocks__/@zowe/imperative.ts

@@ -264,6 +264,9 @@ export class ImperativeError extends Error {
     public get details() {
         return this.mDetails;
     }
+    public get errorCode() {
+        return this.mDetails.errorCode;
+    }
 }
 
 export class ProfInfoErr extends ImperativeError {

packages/zowe-explorer/__tests__/__unit__/trees/dataset/ZoweDatasetNode.unit.test.ts

@@ -1921,7 +1921,7 @@ describe("ZoweDatasetNode Unit Tests - listMembersInRange()", () => {
         jest.spyOn(pdsNode, "listMembers").mockRejectedValue(
             new imperative.ImperativeError({
                 msg: "Dataset not cataloged",
-                errorCode: "404",
+                errorCode: `${imperative.RestConstants.HTTP_STATUS_404}`,
             })
         );