incorrect error message when accessing data sets without permission

[tangthth]

Issue Description:

When accessing VSAM data sets without read or write permission:

• vsam.exist() returns false.
• vsam.openSync() reports error message "TypeError: Invalid dataset name".

Expected Results:

• vsam.exist() returns True.
• vsam.openSync() reports error message indicating SAF violation like no access authority.

Reproduce Steps:

Similar to that of Issue 7, except in Step 1, permit no read or write access.

Logs:

Same as that of Issue 7.

Reference:

Same as that of Issue 7.