This happens when Windup was run against application source, got this error:

**INFO** Executing Rules: :REPORT_RENDERING - org.jboss.windup.reporting:windup-reporting.RenderReportRuleProvider [Uncategorized] GeneratedID_org.jboss.windup.reporting:windup-reporting.RenderReportRuleProvider_1 [1085/1089] ...
**ERROR** Error while executing 'Windup Migrate App'
org.jboss.windup.util.exception.WindupException: Error encountered while evaluating rule: .addRule().when(Query.find(org.jboss.windup.reporting.model.ReportModel).as(default)).perform(Iteration.over.perform(RenderFreeMarkerTemplate)).withId("GeneratedID_org.jboss.windup.reporting:windup-reporting.RenderReportRuleProvider_1")
From: org.jboss.windup.reporting.rules.rendering.RenderReportRuleProvider
Defined in: org.jboss.windup.reporting.rules.rendering.RenderReportRuleProvider.getConfiguration(RenderReportRuleProvider.java:38)
at org.jboss.windup.config.RuleSubset.perform(RuleSubset.java:293)
at org.jboss.windup.exec.WindupProcessorImpl.execute(WindupProcessorImpl.java:91)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor$1.call(ClassLoaderInterceptor.java:87)
at org.jboss.forge.furnace.util.ClassLoaders.executeIn(ClassLoaders.java:42)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor.invoke(ClassLoaderInterceptor.java:103)
at org.jboss.windup.exec.WindupProcessorImpl_$$javassist_d48e9e35-5613-4209-976b-26a2afaf8adc.execute(WindupProcessorImpl$$_javassist_d48e9e35-5613-4209-976b-26a2afaf8adc.java)
at org.jboss.windup.ui.WindupCommand.execute(WindupCommand.java:264)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor$1.call(ClassLoaderInterceptor.java:87)
at org.jboss.forge.furnace.util.ClassLoaders.executeIn(ClassLoaders.java:42)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor.invoke(ClassLoaderInterceptor.java:103)
at org.jboss.windup.ui.WindupCommand_$$javassist_bf4d2c85-7142-4fc9-9ddf-1446c179330f.execute(WindupCommand$$_javassist_bf4d2c85-7142-4fc9-9ddf-1446c179330f.java)
at org.jboss.forge.addon.ui.impl.controller.SingleCommandControllerImpl.execute(SingleCommandControllerImpl.java:90)
at org.jboss.forge.addon.shell.aesh.CommandAdapter.execute(CommandAdapter.java:74)
at org.jboss.aesh.console.AeshConsoleImpl$AeshConsoleCallbackImpl.execute(AeshConsoleImpl.java:325)
at org.jboss.aesh.console.AeshProcess.run(AeshProcess.java:40)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at org.jboss.windup.reporting.freemarker.ProjectModelToApplicationIndexMethod.exec(ProjectModelToApplicationIndexMethod.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor$1.call(ClassLoaderInterceptor.java:87)
at org.jboss.forge.furnace.util.ClassLoaders.executeIn(ClassLoaders.java:42)
at org.jboss.forge.furnace.proxy.ClassLoaderInterceptor.invoke(ClassLoaderInterceptor.java:103)
at org.jboss.windup.reporting.freemarker.ProjectModelToApplicationIndexMethod_$$javassist_d89e2ec9-d2de-4e6c-bc8f-27f8a6bffed1.exec(ProjectModelToApplicationIndexMethod$$_javassist_d89e2ec9-d2de-4e6c-bc8f-27f8a6bffed1.java)
at freemarker.core.MethodCall._eval(MethodCall.java:98)
at freemarker.core.Expression.eval(Expression.java:111)
at freemarker.core.Assignment.accept(Assignment.java:106)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.MixedContent.accept(MixedContent.java:93)
at freemarker.core.Environment.visit(Environment.java:265)
at freemarker.core.Environment.process(Environment.java:243)
at freemarker.template.Template.process(Template.java:277)
at org.jboss.windup.reporting.freemarker.FreeMarkerIterationOperation.perform(FreeMarkerIterationOperation.java:136)
at org.jboss.windup.reporting.freemarker.FreeMarkerIterationOperation.perform(FreeMarkerIterationOperation.java:35)
at org.jboss.windup.config.operation.ruleelement.AbstractIterationOperation.perform(AbstractIterationOperation.java:66)
at org.jboss.windup.config.operation.GraphOperation.perform(GraphOperation.java:24)
at org.jboss.windup.config.operation.Iteration.perform(Iteration.java:236)
at org.jboss.windup.config.operation.Iteration.perform(Iteration.java:200)
at org.ocpsoft.rewrite.config.RuleBuilder.perform(RuleBuilder.java:168)
at org.jboss.windup.config.RuleSubset.perform(RuleSubset.java:225)
... 25 more
**ERROR** Error encountered while evaluating rule: .addRule().when(Query.find(org.jboss.windup.reporting.model.ReportModel).as(default)).perform(Iteration.over.perform(RenderFreeMarkerTemplate)).withId("GeneratedID_org.jboss.windup.reporting:windup-reporting.RenderReportRuleProvider_1")
From: org.jboss.windup.reporting.rules.rendering.RenderReportRuleProvider
Defined in: org.jboss.windup.reporting.rules.rendering.RenderReportRuleProvider.getConfiguration(RenderReportRuleProvider.java:38)