Bug 66425: Avoid a ClassCastException found via oss-fuzz

We try to avoid throwing ClassCastException, but it was possible
to trigger one here with a specially crafted input-file

Should fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=61578

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1911860 13f79535-47bb-0310-9956-ffa450edef68

poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java

             return;
         }
 
-        DocumentEntry entry = (DocumentEntry) getDirectory().getEntry("Pictures");
+        final Entry en = getDirectory().getEntry("Pictures");
+        if (!(en instanceof DocumentEntry)) {
+            throw new IllegalArgumentException("Had unexpected type of entry for name: Pictures: " + en.getClass());
+        }
+        DocumentEntry entry = (DocumentEntry) en;
         EscherContainerRecord blipStore = getBlipStore();
         byte[] pictstream;
         try (DocumentInputStream is = getDirectory().createDocumentInputStream(entry)) {

poi-scratchpad/src/test/java/org/apache/poi/hslf/dev/TestPPTXMLDump.java

 import org.junit.jupiter.api.Test;
 
 import java.io.File;
+import java.io.IOException;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
     static final Set<String> LOCAL_EXCLUDED = new HashSet<>();
     static {
         LOCAL_EXCLUDED.add("clusterfuzz-testcase-minimized-POIHSLFFuzzer-5306877435838464.ppt");
+        LOCAL_EXCLUDED.add("clusterfuzz-testcase-minimized-POIHSLFFuzzer-6032591399288832.ppt");
     }
 
     @Test
     void runOneFile(File pFile) throws Exception {
         try {
            PPTXMLDump.main(new String[]{pFile.getAbsolutePath()});
-        } catch (IndexOutOfBoundsException e) {
+        } catch (IndexOutOfBoundsException | IOException e) {
             if (!LOCAL_EXCLUDED.contains(pFile.getName())) {
                 throw e;
             }