Fix some return FALSE in functions that return pointers

fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp

Index: fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
index 13b79baf9bba2924eafe75eda8cc226c28c2c9cb..2a2bb3c48daadb994a2e903e8dcd907c7f43f9e0 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
@@ -709,16 +709,16 @@ IFX_SeekableReadStream* CPDFXFA_DocEnvironment::OpenLinkedFile(
     const CFX_WideString& wsLink) {
   CPDFSDK_FormFillEnvironment* pFormFillEnv = m_pDocument->GetFormFillEnv();
   if (!pFormFillEnv)
-    return FALSE;
+    return nullptr;
 
   CFX_ByteString bs = wsLink.UTF16LE_Encode();
   int len = bs.GetLength();
   FPDF_FILEHANDLER* pFileHandler =
       pFormFillEnv->OpenFile(0, (FPDF_WIDESTRING)bs.GetBuffer(len), "rb");
   bs.ReleaseBuffer(len);
-
   if (!pFileHandler)
     return nullptr;
+
   return new CFPDF_FileStream(pFileHandler);
 }