cmd/app: display user-facing error message

This is required for useful error messages for errors originating from internal/store.

Signed-off-by: Ophestra <cat@gensokyo.uk>

cmd/app/main.go

@@ -222,7 +222,13 @@ func main() {
 		}
 
 		if w, ok := err.(interface{ Unwrap() []error }); !ok {
-			log.Fatal(err)
+			var m string
+			m, ok = message.GetMessage(err)
+			if !ok {
+				log.Fatal(err)
+				return
+			}
+			log.Fatal(m)
 		} else {
 			errs := w.Unwrap()
 			for i, e := range errs {