[ARCHETYPE-585] Fix NullPointerException
diff --git a/archetype-common/src/main/java/org/apache/maven/archetype/source/RemoteCatalogArchetypeDataSource.java b/archetype-common/src/main/java/org/apache/maven/archetype/source/RemoteCatalogArchetypeDataSource.java
index 095ff8e..d802e6a 100644
--- a/archetype-common/src/main/java/org/apache/maven/archetype/source/RemoteCatalogArchetypeDataSource.java
+++ b/archetype-common/src/main/java/org/apache/maven/archetype/source/RemoteCatalogArchetypeDataSource.java
@@ -296,13 +296,18 @@
     {
         MavenSession session = legacySupport.getSession();
 
-        MavenExecutionRequest request = session.getRequest();
+        MavenExecutionRequest request = null;
+
+        if ( session != null )
+        {
+            request = session.getRequest();
+        }
 
         if ( request != null )
         {
             return getMirror( repoId, request.getMirrors() );
         }
-        
+
         return null;
     }