[Minor] Add fail-safety for settings post load

lualib/lua_settings.lua

@@ -32,6 +32,10 @@ local lua_util = require "lua_util"
 local rspamd_logger = require "rspamd_logger"
 
 local function register_settings_cb(from_postload)
+  if not from_postload then
+    assert(false, 'invalid invocation')
+  end
+
   if not post_init_performed then
     all_symbols = rspamd_config:get_symbols()
 

src/lua/lua_task.c

@@ -5774,7 +5774,7 @@ lua_task_set_settings_id (lua_State *L)
 				rspamd_config_find_settings_id_ref (task->cfg, id);
 
 		if (selt == NULL) {
-			return luaL_error (L, "settings id %u is unknown", id);
+			return luaL_error (L, "settings id %f is unknown", (lua_Number)id);
 		}
 		if (task->settings_elt) {
 			/* Overwrite existing settings from Lua */