Errors in command should not cause application to exit

[vrajat]

For example AccessDeniedException causes the application to fail.

\r:iamdb> grant SELECT ON TABLE '*****' TO '****';
.....
    raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (AccessDeniedException) when calling the GrantPermissions operation: Insufficient Lake Formation permission(s) on ******

During handling of the above exception, another exception occurred:
.....
except OperationalError as e:
NameError: name 'OperationalError' is not defined