more native without fallback

internal/engine.cm

@@ -644,7 +644,7 @@ function use_core(path) {
         result = mach_load(mach_blob, env)
       }
     } disruption {
-      os.print("use('" + path + "'): failed to compile or load " + file_path + "\n")
+      log.error("use('" + path + "'): failed to compile or load " + file_path)
       disrupt
     }
     _load_mod()
@@ -1712,7 +1712,6 @@ $_.clock(_ => {
   }
 
   env.use = function(path) {
-    if (path == 'prosperon/compositor') log.shop('DEBUG engine env.use: pkg=' + (pkg || '(null)'))
     var ck = 'core/' + path
     var _use_core_result = null
     var _use_core_ok = false