[Launching] Only set project-name if IProject is existing IJavaProject

Fixes #1293

Author: HannesWell

org.eclipse.m2e.launching/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Bundle-Name
 Bundle-SymbolicName: org.eclipse.m2e.launching;singleton:=true
-Bundle-Version: 2.0.300.qualifier
+Bundle-Version: 2.0.400.qualifier
 Bundle-Localization: plugin
 Require-Bundle: org.eclipse.core.runtime,
  org.eclipse.core.variables,

org.eclipse.m2e.launching/src/org/eclipse/m2e/internal/launch/MavenLaunchDelegate.java

@@ -44,6 +44,7 @@
 import org.eclipse.debug.core.ILaunch;
 import org.eclipse.debug.core.ILaunchConfiguration;
 import org.eclipse.debug.core.ILaunchConfigurationWorkingCopy;
+import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.launching.IJavaLaunchConfigurationConstants;
 import org.eclipse.jdt.launching.IVMInstall;
 import org.eclipse.jdt.launching.IVMInstall2;
@@ -228,7 +229,8 @@ public IVMInstall getVMInstall(ILaunchConfiguration configuration) throws CoreEx
         }
       }
     }
-    Optional<IProject> project = getContainer(pomDirectory).map(IContainer::getProject);
+    Optional<IProject> project = getContainer(pomDirectory).map(IContainer::getProject)
+        .filter(p -> JavaCore.create(p).exists());
     if(project.isPresent()) {
       // Set the project name so that super.getVMInstall() called below, can find the JDT-Compiler JDK 
       ILaunchConfigurationWorkingCopy workingCopy = configuration.getWorkingCopy();