NullPointerException at com.eviware.soapui.impl.wsdl.teststeps.RestTestRequestStep

I am stuck with below error . I am calling a groovy test step from assertion of a Test Step and this groovy test step is calling another test case . it is running but below exception is coming .

Just sample code .

Test Step 1 - >  In assertion calling another test step based on some conditions

     context.testCase.getTestStepByName("VerifyAddress").run(context.testRunner,context)

Test step 2 (VerifyAddress)

      //calling another step based on few conditions

     def key = context.testCase.testSuite.project.testSuites['Keywords_Addresses'].testCases['ApproveAdress']

     key.setPropertyValue("city",city)

     def runner = key.run( null, true )
     runner.waitUntilFinished()

Thu Apr 29 22:53:32 IST 2021: ERROR: java.lang.NullPointerException java.lang.NullPointerException at com.eviware.soapui.impl.wsdl.teststeps.RestTestRequestStep.run(RestTestRequestStep.java:921) at com.eviware.soapui.model.testsuite.TestStep$run$0.call(Unknown Source) at Script7.run(Script7.groovy:14) at com.eviware.soapui.support.scripting.groovy.SoapUIGroovyScriptEngine.run(SoapUIGroovyScriptEngine.java:94) at com.eviware.soapui.support.scripting.groovy.SoapUIProGroovyScriptEngineFactory$SoapUIProGroovyScriptEngine.run(SoapUIProGroovyScriptEngineFactory.java:83) at com.eviware.soapui.impl.wsdl.teststeps.assertions.basic.GroovyScriptAssertion.assertScript(GroovyScriptAssertion.java:150) at com.eviware.soapui.impl.wsdl.teststeps.assertions.basic.GroovyScriptAssertion.internalAssertResponse(GroovyScriptAssertion.java:186) at com.eviware.soapui.impl.wsdl.teststeps.WsdlMessageAssertion.assertResponse(WsdlMessageAssertion.java:164) at com.eviware.soapui.impl.wsdl.teststeps.RestTestRequest.assertResponse(RestTestRequest.java:150) at com.eviware.soapui.impl.wsdl.teststeps.RestTestRequest.setResponse(RestTestRequest.java:141) at com.eviware.soapui.impl.support.panels.AbstractHttpRequestDesktopPanel.afterSubmit(AbstractHttpRequestDesktopPanel.java:606) at com.eviware.soapui.impl.wsdl.panels.teststeps.RestTestRequestDesktopPanel.afterSubmit(RestTestRequestDesktopPanel.java:365) at com.eviware.soapui.impl.wsdl.WsdlSubmit.notifyListenersAfterSubmit(WsdlSubmit.java:111) at com.eviware.soapui.impl.wsdl.WsdlSubmit.run(WsdlSubmit.java:157) at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at java.base/java.lang.Thread.run(Thread.java:835)