groovy - Jenkins Email-ext plugin exception raised during template rendering -

i using jenkins email-ext plugin , part works great, every , exception raised during template rendering: null java.lang.nullpointerexception errors. these errors seem occur when server under higher load, hard pin down exactly.

exception raised during template rendering: null java.lang.nullpointerexception      @ org.codehaus.groovy.runtime.callsite.geteffectivepojopropertysite.acceptgetproperty(geteffectivepojopropertysite.java:51)      @ org.codehaus.groovy.runtime.callsite.abstractcallsite.callgetproperty(abstractcallsite.java:227) @ simpletemplatescript3$_run_closure1.docall(simpletemplatescript3.groovy:143)      @ sun.reflect.nativemethodaccessorimpl.invoke0(native method)      @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:57)      @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:43)      @ java.lang.reflect.method.invoke(method.java:606)      @ org.codehaus.groovy.reflection.cachedmethod.invoke(cachedmethod.java:90)      @ groovy.lang.metamethod.domethodinvoke(metamethod.java:233)      @ org.codehaus.groovy.runtime.metaclass.closuremetaclass.invokemethod(closuremetaclass.java:272)      @ groovy.lang.metaclassimpl.invokemethod(metaclassimpl.java:903)     @ groovy.lang.closure.call(closure.java:415)      @ groovy.lang.closure.call(closure.java:428)      @ org.codehaus.groovy.runtime.defaultgroovymethods.each(defaultgroovymethods.java:1379)      @ org.codehaus.groovy.runtime.defaultgroovymethods.each(defaultgroovymethods.java:1351)      @ org.codehaus.groovy.runtime.dgm$170.invoke(unknown source)      @ org.codehaus.groovy.runtime.callsite.pojometamethodsite$pojometamethodsitenounwrapnocoerce.invoke(pojometamethodsite.java:271)      @ org.codehaus.groovy.runtime.callsite.pojometamethodsite.call(pojometamethodsite.java:53)      @ org.codehaus.groovy.runtime.callsite.abstractcallsite.call(abstractcallsite.java:116)      @ simpletemplatescript3.run(simpletemplatescript3.groovy:140)      @ groovy.text.simpletemplateengine$simpletemplate$1.writeto(simpletemplateengine.java:165)      @ groovy.text.simpletemplateengine$simpletemplate$1.tostring(simpletemplateengine.java:177)      @ hudson.plugins.emailext.plugins.content.scriptcontent.rendertemplate(scriptcontent.java:193)      @ hudson.plugins.emailext.plugins.content.scriptcontent.evaluate(scriptcontent.java:80)      @ org.jenkinsci.plugins.tokenmacro.databoundtokenmacro.evaluate(databoundtokenmacro.java:189)      @ org.jenkinsci.plugins.tokenmacro.tokenmacro.expand(tokenmacro.java:182)      @ org.jenkinsci.plugins.tokenmacro.tokenmacro.expandall(tokenmacro.java:233)      @ hudson.plugins.emailext.plugins.contentbuilder.transformtext(contentbuilder.java:71)      @ hudson.plugins.emailext.extendedemailpublisher.getcontent(extendedemailpublisher.java:717)      @ hudson.plugins.emailext.extendedemailpublisher.createmail(extendedemailpublisher.java:474)      @ hudson.plugins.emailext.extendedemailpublisher.sendmail(extendedemailpublisher.java:292)      @ hudson.plugins.emailext.extendedemailpublisher._perform(extendedemailpublisher.java:283)      @ hudson.plugins.emailext.extendedemailpublisher.perform(extendedemailpublisher.java:235)      @ hudson.tasks.buildstepmonitor$1.perform(buildstepmonitor.java:20)      @ hudson.model.abstractbuild$abstractbuildexecution.perform(abstractbuild.java:804)      @ hudson.model.abstractbuild$abstractbuildexecution.performallbuildsteps(abstractbuild.java:776)      @ hudson.model.build$buildexecution.cleanup(build.java:192)      @ hudson.model.run.execute(run.java:1721)      @ hudson.model.freestylebuild.run(freestylebuild.java:43)      @ hudson.model.resourcecontroller.execute(resourcecontroller.java:88)      @ hudson.model.executor.run(executor.java:231)  

has else seen errors , if how did resolve it?

thanks!