strange JSNI Exception "Something other than a Java object was returned from JSNI method ...: JS value of type boolean, expected java.lang.Object"

[tanteanni]

our gwt produces every few seconds a strange exception:
"java.lang.IllegalArgumentException: Something other than a Java object was returned from JSNI method"

i googled around and find that this could be related to autoboxing (in this case probably boolean<->Boolean: "JS value of type boolean, expected java.lang.Object"). The question is: is autoboxing allowed in client code? is this a limitation of gwt? i never read about such an limitation and most of google results about that are outdated.
Ok now i found this: http://googlewebtoolkit.blogspot.com/2008/08/gwt-15-now-available.html -"Simplify your code with for-each loops, autoboxing, static imports, and enum types".

So what is the problem here or how to debug this?

thx in advance

Full stack trace:

java.lang.IllegalArgumentException: Something other than a Java object was returned from JSNI method '@com.google.gwt.core.client.impl.Impl::apply(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)': JS value of type boolean, expected java.lang.Object
    at com.google.gwt.dev.shell.JsValueGlue.get(JsValueGlue.java:178)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:271)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214)
    at sun.reflect.GeneratedMethodAccessor118.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
    at java.lang.Thread.run(Thread.java:619)
Wed Oct 26 07:04:23 CEST 2011
SEVERE: class java.lang.IllegalArgumentException null
com.google.gwt.dev.shell.JsValueGlue.get(JsValueGlue.java:178)
com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:271)
com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
com.google.gwt.core.client.impl.Impl.apply(Impl.java)
com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214)
sun.reflect.GeneratedMethodAccessor118.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:597)
com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:167)
com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
java.lang.Thread.run(Thread.java:619)

[Thomas Broyer]

Looks a lot like http://code.google.com/p/google-web-toolkit/issues/detail?id=5778

Does it only happen in Chrome, or on other browsers too?

[tanteanni]

i think yes -

thx for the hint