All of a sudden I'm getting an IllegalArgumentException debugging a GWT app in DevMode. I'm using 2.6.1. It isn't clear to me what can cause this or how to debug the cause. It seems somewhat random in its occurrence but seems to happen less if breakpoints are used. What might be the cause of this?
SEVERE: 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
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)
com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:286)
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:356)
sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:606)
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:172)
com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:338)
com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:219)
com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:576)
com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:284)
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:356)
sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
...
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:286)
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:356)
at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
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:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:338)
at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:219)
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:576)
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:284)
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:356)
at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
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:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:293)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:547)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
at java.lang.Thread.run(Thread.java:724)