FOP-2321: Latest fop snapshot crashes when processing rindolf-spec.fo

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1572109 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/fop/render/rtf/RTFHandler.java

@@ -218,8 +218,10 @@ public class RTFHandler extends FOEventHandler {
                     eventProducer.onlySPMSupported(this, reference, pageSeq.getLocator());
                     PageSequenceMaster master
                         = pageSeq.getRoot().getLayoutMasterSet().getPageSequenceMaster(reference);
-                    this.pagemaster = master.getNextSimplePageMaster(
-                            false, false, false, false, pageSeq.getMainFlow().getFlowName());
+                    if (pageSeq.getMainFlow() != null) {
+                        this.pagemaster = master.getNextSimplePageMaster(
+                                false, false, false, false, pageSeq.getMainFlow().getFlowName());
+                    }
                 }
             }