Second launch of IDE fails

[nedtwigg]

Here is an example stacktrace

[main] INFO dev.equo.solstice.Solstice - activate org.eclipse.jdt.core
Exception in thread "main" java.lang.NoClassDefFoundError: Could not initialize class org.eclipse.jdt.internal.core.JavaModelManager
        at org.eclipse.jdt.core.JavaCore.start(JavaCore.java:6477)
        at dev.equo.solstice.ShimBundle.activate(ShimBundle.java:166)
        at dev.equo.solstice.ShimBundle.start(ShimBundle.java:132)
        at dev.equo.solstice.Solstice.start(Solstice.java:453)
        at dev.equo.solstice.Solstice.start(Solstice.java:407)
        at dev.equo.solstice.Solstice.start(Solstice.java:446)
        at dev.equo.solstice.Solstice.start(Solstice.java:407)
        at dev.equo.solstice.Solstice.startAllWithLazy(Solstice.java:369)
        at dev.equo.ide.IdeMainUi$1.initialize(IdeMainUi.java:73)
        at org.eclipse.ui.application.WorkbenchAdvisor.internalBasicInitialize(WorkbenchAdvisor.java:171)
        at org.eclipse.ui.internal.Workbench$18.runWithException(Workbench.java:1615)
        at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:36)
        at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:183)
        at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:133)
        at org.eclipse.swt.widgets.Display.syncExec(Display.java:4803)
        at org.eclipse.ui.internal.StartupThreading.runWithoutExceptions(StartupThreading.java:94)
        at org.eclipse.ui.internal.Workbench.init(Workbench.java:1611)
        at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2748)
        at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:636)
        at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
        at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:550)
        at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:171)
        at dev.equo.ide.IdeMainUi.main(IdeMainUi.java:68)
        at dev.equo.ide.BuildPluginIdeMain.main(BuildPluginIdeMain.java:416)
Caused by: java.lang.ExceptionInInitializerError: Exception java.lang.NullPointerException [in thread "Worker-1: Building"]
        at org.eclipse.jdt.internal.core.search.indexing.IndexManager.getJavaPluginWorkingLocation(IndexManager.java:624)
        at org.eclipse.jdt.internal.core.search.indexing.IndexManager.getSavedIndexesDirectory(IndexManager.java:628)
        at org.eclipse.jdt.internal.core.search.indexing.IndexManager.<init>(IndexManager.java:125)
        at org.eclipse.jdt.internal.core.JavaModelManager.<init>(JavaModelManager.java:1777)
        at org.eclipse.jdt.internal.core.JavaModelManager.<clinit>(JavaModelManager.java:1207)
        at org.eclipse.jdt.core.JavaCore.create(JavaCore.java:3669)
        at org.eclipse.jdt.internal.core.DynamicProjectReferences.getDependentProjects(DynamicProjectReferences.java:33)
        at org.eclipse.core.internal.resources.ProjectDescription.computeDynamicReferencesForProject(ProjectDescription.java:951)
        at org.eclipse.core.internal.resources.ProjectDescription.getAllBuildConfigReferences(ProjectDescription.java:266)
        at org.eclipse.core.internal.resources.Project.internalGetReferencedBuildConfigs(Project.java:797)
        at org.eclipse.core.internal.resources.Workspace.computeActiveBuildConfigGraph(Workspace.java:777)
        at org.eclipse.core.internal.resources.Workspace.getBuildGraph(Workspace.java:1634)
        at org.eclipse.core.internal.resources.Workspace.getBuildOrder(Workspace.java:1615)
        at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:196)
        at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:289)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

The fix is to do gradlew equoIde --clean.