Assert that only 0-numbered objects are Released()

core/fpdfapi/fpdf_parser/cpdf_array.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_array.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_array.cpp b/core/fpdfapi/fpdf_parser/cpdf_array.cpp
index 26e65bca3463def701abd0130af9eba67f87ca39..a3be55b9f0cb1977e6073245f8c760ccadf6bcd6 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_array.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_array.cpp
@@ -23,7 +23,7 @@ CPDF_Array::~CPDF_Array() {
   // in case of cyclic references.
   m_ObjNum = kInvalidObjNum;
   for (auto& it : m_Objects) {
-    if (it)
+    if (it && it->GetObjNum() != kInvalidObjNum)
       it->Release();
   }
 }