[Tooling] Guard against null pointer while deleting src-gen

The now used findMember method will return null if the resource does not
exist (and, thus, does not have to be deleted anyway).
Furthermore, it will return the container itself if the path is empty.
Hence, the if statement is not needed.

de.wwu.md2.framework.ui/src/de/wwu/md2/framework/ui/generator/ExtendedEclipseResourceFileSystemAccess2.java

@@ -183,11 +183,9 @@ public void deleteDirectory(String directoryName, String outputConfiguration) {
 		try {
 			directoryName = directoryName.replaceAll("^/", "");
 			IContainer folder = getContainer(outputConfig);
-			IResource toDelete = folder;
-			if(!directoryName.isEmpty()) {
-				toDelete = folder.findMember(directoryName);
-			}
-			toDelete.delete(IResource.KEEP_HISTORY, getMonitor());
+			IResource toDelete = folder.findMember(directoryName);
+			if(toDelete != null)
+				toDelete.delete(IResource.KEEP_HISTORY, getMonitor());
 		} catch (CoreException e) {
 			throw new RuntimeException(e);
 		}