Ensures call stack location object exists before calling methods on it

Fixes the error:
TypeError: Cannot call method 'getFunctionName' of undefined

In longjohn.js:call_stack_location(), if the object stack[2] is not defined it crashes the server with an uncaught exception.

Signed-off-by: Jim Knochelmann <jim@airspringsoftware.com>
Ensures call stack location object exists before calling methods on it (for coffee-script)

Signed-off-by: Jim Knochelmann <jim@airspringsoftware.com>
Merge pull request #27 from jimknoc/master

Ensures call stack location object exists before calling methods on it