#453 all exceptions are not handled, and all message is CUBRIDException was unhandled by user code

[Jira Trac]

Reproduced steps:
1. Create a CUBRID connection
2. Provide connection string to open a connection
3. Close this connection again
4. try to use that connection

Result:
message CUBRIDException was unhandled by user code, all exception message are not handled.

Expected result:
Provide a clear error/exception message to user when error/exception happens