tmf: Log the exception when error occurs while opening a trace

tmf: Log the exception when error occurs while opening a trace

If an exception occurs when opening a trace, the exception message
is displayed but the stack is nowhere to be found. By logging the
exception, the stack trace will be available in the log.

Change-Id: I8085cb46a1657747cc2f2be5736e4b17e0b7040f
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/79792
Reviewed-by: Hudson CI