Silent exception catch cause false answer in doesStreamExists method

Catching silently the exception thrown by launcher.run and then parsing the command output cause the doesStreamExists method to return true in the case the command failed with error, since the output will not contain "stream not found" but instead the command error message.

In case of a command error, we do not know if the stream exists or not, so returning either true or false is incorrect. This fix is preventing this behavior.