building with dart2js is causing strange error with package logging

[jimmyff]

I've been using the logging package for months but suddenly I'm running in to issues with it when building with dart2js:

  js_helper.dart:1772 Uncaught Error: NoSuchMethodError: method not found: 'call$0' (message.call$0 is not a function)
    at Logger.log$5 (logging.dart:170)
    at Logger.log$4 (main.dart.js:172577)
    at logging.dart:218
    at _wrapJsFunctionForAsync_closure.$protected (async_patch.dart:213)
    at _wrapJsFunctionForAsync_closure.call$2 (async_patch.dart:237)
    at _awaitOnObject_closure.call$1 (async_patch.dart:187)
    at _RootZone.runUnary$2 (zone.dart:1371)
    at _Future__propagateToListeners_handleValueCallback.call$0 (future_impl.dart:129)
    at Object._Future__propagateToListeners (future_impl.dart:665)
    at _Future__addListener_closure.call$0 (future_impl.dart:343)

This is logging package code that the exception is pointing to:

 void log(Level logLevel, message,
      [Object error, StackTrace stackTrace, Zone zone]) {
    Object object;
    if (isLoggable(logLevel)) {
      if (message is Function) message = message();

I added some debug:

  void log(Level logLevel, message,
      [Object error, StackTrace stackTrace, Zone zone]) {
    Object object;
    print ('level: $logLevel message: ${message.toString()} is function: ${(message is Function).toString()}');
    print (message);
    if (isLoggable(logLevel)) {
      if (message is Function) message = message();

It seems that this is failing on the first time it's called. It prints the following to the console before it fails:

13:48:51.772 level: INFO message: endpoint:api.mydomain.com/v3.1/ hash:no is function: true
13:48:51.802 endpoint:api.mydomain.com/v3.1/ hash:no

It's very strange that is thinks this String is a Function - In Dartium there is no issue and it prints false when checking if the message is a function.

This is the code I use to make that first log call (this has worked for months up until last week):

  _log.info('endpoint:${config.api} hash:${config.hashRouting?'yes':'no'}');

[matanlurey]

@jimmyff Consider trying the latest Dart2JS (with --preview-dart-2) and open if persists.