* load.c (scm_sys_try_load): don't check whether value returned

by scm_open_file is #f, it won't be.  Always return SCM_UNSPECIFIED.
Change the Scheme name from %try-load to primitive-load.

* error.c (scm_error): convert a NULL message to SCM_BOOL_F.
Can avoid passing a message, allowing it to be derived in the
error handler (e.g., if we want to throw to the key both from
Scheme and C).

libguile/error.c

@@ -137,7 +137,7 @@ scm_error (key, subr, message, args, rest)
     (*scm_error_callback) (key, subr, message, args, rest);
 
   arg_list = scm_listify (subr ? scm_makfrom0str (subr) : SCM_BOOL_F,
-			  scm_makfrom0str (message),
+			  message ? scm_makfrom0str (message) : SCM_BOOL_F,
 			  args,
 			  rest,
 			  SCM_UNDEFINED);