ref #166 switched approach to throwing exception and triggering a ful…

…l xref scan, instead of silently ignoring problematic xref entry line;

src/main/java/org/sejda/sambox/input/XrefParser.java

@@ -90,14 +90,11 @@ void onEntryFound(XrefEntry entry)
             {
                 if(entry.getByteOffset() < XrefEntry.UNKNOWN_OFFSET)
                 {
-                    LOG.warn("Ignoring xrefEntry with negative byteOffset: {}", entry);
+                    // throw an error instead of silently skipping to force the XrefFullScanner
+                    throw new IllegalArgumentException("XrefEntry with negative byteOffset: " + entry.getByteOffset());
                 }
-                else
-                {
-                    parser().provider().addEntryIfAbsent(entry);
-                }
-
-
+
+                parser().provider().addEntryIfAbsent(entry);
             }
         };
     }

src/test/java/org/sejda/sambox/input/PDFParserTest.java

@@ -521,6 +521,8 @@ public void testNegativeOffsetXrefEntry() throws IOException
 
             PDFTextStripper textStripper = new PDFTextStripper();
             textStripper.getText(doc);
+
+            assertTrue(doc.hasParseErrors());
         }
     }