We have been successfully running GWT Unit Tests using SmartGWT 6.1.

However, after switching to SmartGWT 13.0
we are experiencing the following error:

Code:
com.google.gwt.core.client.JavaScriptException: (TypeError) : Cannot read property "Dialog" from undefined
    at com.smartgwt.client.util.I18nUtil.initMessages(I18nUtil.java:198)
    at com.smartgwt.client.util.I18nUtil.init(I18nUtil.java:32)
    at com.smartgwt.client.SmartGwtEntryPoint.$onModuleLoad(SmartGwtEntryPoint.java:517)
    at com.google.gwt.junit.client.GWTTestCase.$runBare(GwtTestGenerateJSONFilterCriteria.java:22)
    at com.google.gwt.junit.client.GWTTestCase.$__doRunTest(GWTTestCase.java:115)
    at com.google.gwt.junit.client.impl.GWTRunner.$runTest(GWTRunner.java:302)
    at com.google.gwt.junit.client.impl.GWTRunner.$doRunTest(GWTRunner.java:235)
    at com.google.gwt.junit.client.impl.GWTRunner$TestBlockListener.$onSuccess(GWTRunner.java:106)
    at com.google.gwt.junit.client.impl.GWTRunner$TestBlockListener.onSuccess(GWTRunner.java:100)
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.$onResponseReceived(RequestCallbackAdapter.java:232)
    at com.google.gwt.http.client.Request.$fireOnResponseReceived(Request.java:250)
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:412)
    at Unknown.anonymous(XMLHttpRequest.java:329)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java:309)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:368)
    at Unknown.anonymous(Impl.java:78)