templater: give better error message for invalid engine type...
templater: give better error message for invalid engine type
Before, KeyError was caught at changeset_templater._show(), which said "no
key named '%s'" as it was intended to catch the KeyError of unknown map key.
Instead, we should catch KeyError explicitly for better error indication.
For those who don't know what the template engine is (read "everyone"), it is
hidden extension feature that allows switching template syntax in map file.
See
d8c5a7f25a40 for details.
