exception: catch by reference

`catch` should always be done by reference to avoid object slicing and
excess copy-constructor calls.  Preference is for exceptions to also
be caught 'const'.  (Both of these come from the C++ Core Guidelines)

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic8cd1e138220e501699525e9c8d53cd581e2598c
1 file changed