changed a catch block to the preferred way for showing information about AsuraException.

After AsuraException::getFancyMessage() was added, using it is
the coding policy.

Advanteges of getFacnyMessage() are the following.
- Can show information added after the catch block is written.
- Can control output parameters (e.g. turing on/off of stack trace)
  with the unified way such as an environment variable.
- Can make a catch block short.