error make initdb if xz isn't installed (#5872)

This threw me for a loop getting warehouse setup on my new laptop! `make initdb` was silently failing.

Author: ewdurbin

Makefile

@@ -149,6 +149,9 @@ ifneq ($(PR), false)
 endif
 
 initdb:
+	ifeq (, $(shell which xz))
+	$(error "No xz available on PATH, install xz-utils!")
+	endif
 	docker-compose run --rm web psql -h db -d postgres -U postgres -c "DROP DATABASE IF EXISTS warehouse"
 	docker-compose run --rm web psql -h db -d postgres -U postgres -c "CREATE DATABASE warehouse ENCODING 'UTF8'"
 	xz -d -f -k dev/$(DB).sql.xz --stdout | docker-compose run --rm web psql -h db -d warehouse -U postgres -v ON_ERROR_STOP=1 -1 -f -