Type check the m_pShadingObj before assuming it's a stream.

core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp

Index: core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
index 7b04d8cd3375139136db8654b8e5e67a247964c5..ded6c878ea909fa283f8291cf89e3db5f393b0f5 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_pattern.cpp
@@ -140,6 +140,11 @@ FX_BOOL CPDF_ShadingPattern::Load() {
     m_pCountedCS = pDocPageData->FindColorSpacePtr(m_pCS->GetArray());
   }
   m_ShadingType = pShadingDict->GetInteger(FX_BSTRC("ShadingType"));
+
+  // We expect to have a stream if our shading type is a mesh.
+  if (m_ShadingType >= 4 && !ToStream(m_pShadingObj))
+    return FALSE;
+
   return TRUE;
 }
 FX_BOOL CPDF_ShadingPattern::Reload() {