server: Fix NPE when deleting a trace

[Fixed] NullPointerException when deleting a trace from the trace server

Change-Id: I2b0a8566a2e2b423f86853fd17c956e0fb1e487b
Signed-off-by: Bernd Hufmann <Bernd.Hufmann@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/150557
Tested-by: CI Bot
Reviewed-by: Simon Delisle <simon.delisle@ericsson.com>
Tested-by: Simon Delisle <simon.delisle@ericsson.com>
diff --git a/trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/services/TraceManagerService.java b/trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/services/TraceManagerService.java
index e24eda0..fa8bc1d 100644
--- a/trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/services/TraceManagerService.java
+++ b/trace-server/org.eclipse.tracecompass.incubator.trace.server.jersey.rest.core/src/org/eclipse/tracecompass/incubator/internal/trace/server/jersey/rest/core/services/TraceManagerService.java
@@ -215,10 +215,13 @@
         TmfTraceManager.deleteSupplementaryFolder(trace);
         trace.dispose();
         try {
-            trace.getResource().delete(IResource.FORCE, null);
+            IResource resource = trace.getResource();
+            if (resource != null) {
+                resource.delete(IResource.FORCE, null);
+            }
             ResourcesPlugin.getWorkspace().getRoot()
-                    .getProject(TmfCommonConstants.DEFAULT_TRACE_PROJECT_NAME)
-                    .refreshLocal(Integer.MAX_VALUE, null);
+                .getProject(TmfCommonConstants.DEFAULT_TRACE_PROJECT_NAME)
+                .refreshLocal(Integer.MAX_VALUE, null);
         } catch (CoreException e) {
             Activator.getInstance().logError("Failed to delete trace", e); //$NON-NLS-1$
         }