NullPointer logged when no coverage is parsed from Clover

java.lang.NullPointerException
        at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:991)
        at java.lang.Double.parseDouble(Double.java:482)
        at com.atlassian.bamboo.builder.coverage.CloverDeltaCalculator.call(CloverDeltaCalculator.java:40)
        at sun.reflect.GeneratedMethodAccessor313.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
        at org.springframework.orm.hibernate.HibernateInterceptor.invoke(HibernateInterceptor.java:117)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
        at $Proxy46.call(Unknown Source)
        at com.atlassian.bamboo.v2.build.agent.LocalBuildResultProcessor.performCustomBuildProcessServer(LocalBuildResultProcessor.java:150)
        at com.atlassian.bamboo.v2.build.agent.LocalBuildResultProcessor.processBuildResult(LocalBuildResultProcessor.java:66)
        at com.atlassian.bamboo.v2.build.agent.BuildAgentControllerImpl.waitAndPerformBuild(BuildAgentControllerImpl.java:108)
        at com.atlassian.bamboo.v2.build.agent.DefaultBuildAgent$1.run(DefaultBuildAgent.java:101)
        at com.atlassian.bamboo.build.pipeline.concurrent.NamedThreadFactory$1.run(NamedThreadFactory.java:32)
        at edu.emory.mathcs.backport.java.util.concurrent.helpers.ThreadHelpers$1.run(ThreadHelpers.java:34)
        at java.lang.Thread.run(Thread.java:595)