Issue #6497 - aliasChecker with no baseResource should always denies …

…aliases

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

jetty-server/src/main/java/org/eclipse/jetty/server/AllowedResourceAliasChecker.java

@@ -76,9 +76,6 @@ protected Path getBasePath()
     protected void doStart() throws Exception
     {
         _basePath = getPath(_contextHandler.getBaseResource());
-        if (_basePath == null)
-            throw new IllegalStateException("Could not obtain base resource path");
-
         String[] protectedTargets = _contextHandler.getProtectedTargets();
         if (protectedTargets != null)
         {
@@ -99,6 +96,9 @@ protected void doStop() throws Exception
     @Override
     public boolean check(String uri, Resource resource)
     {
+        if (_basePath == null)
+            return false;
+
         // The existence check resolves the symlinks.
         if (!resource.exists())
             return false;