Remove "this==NULL" and adjust corresponding callers

core/src/fpdfdoc/doc_formfield.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../include/fpdfdoc/fpdf_doc.h"
 CFX_WideString          GetFullName(CPDF_Dictionary* pFieldDict);
 void                            SaveCheckedFieldStatus(CPDF_FormField* pField, CFX_ByteArray& statusArray);
 FX_BOOL PDF_FormField_IsUnison(CPDF_FormField *pField)
@@ skipping 14 matching lines @@
     m_pForm = pForm;
     m_pFont = NULL;
     m_FontSize = 0;
     SyncFieldFlags();
 }
 CPDF_FormField::~CPDF_FormField()
 {
 }
 void CPDF_FormField::SyncFieldFlags()
 {
-    CFX_ByteString type_name = FPDF_GetFieldAttr(m_pDict, "FT")->GetString();
-    FX_DWORD flags = FPDF_GetFieldAttr(m_pDict, "Ff")->GetInteger();
+    CFX_ByteString type_name = FPDF_GetFieldAttr(m_pDict, "FT") ? FPDF_GetFieldAttr(m_pDict, "FT")->GetString() : CFX_ByteString();
+    FX_DWORD flags = FPDF_GetFieldAttr(m_pDict, "Ff")? FPDF_GetFieldAttr(m_pDict, "Ff")->GetInteger() : 0;
     m_Flags = 0;
     if (flags & 1) {
         m_Flags |= FORMFIELD_READONLY;
     }
     if (flags & 2) {
         m_Flags |= FORMFIELD_REQUIRED;
     }
     if (flags & 4) {
         m_Flags |= FORMFIELD_NOEXPORT;
     }
@@ skipping 431 matching lines @@
         sel_value = pValue->GetUnicodeText();
     } else if (pValue->GetType() == PDFOBJ_NUMBER) {
         return pValue->GetInteger();
     } else {
         if (pValue->GetType() != PDFOBJ_ARRAY) {
             return -1;
         }
         if (index < 0) {
             return -1;
         }
-        sel_value = ((CPDF_Array*)pValue)->GetElementValue(index)->GetUnicodeText();
+        CPDF_Object* elementValue = ((CPDF_Array*)pValue)->GetElementValue(index);
+        sel_value = elementValue ? elementValue->GetUnicodeText() : CFX_WideString();
     }
     if (index < CountSelectedOptions()) {
         int iOptIndex = GetSelectedOptionIndex(index);
         CFX_WideString csOpt = GetOptionValue(iOptIndex);
         if (csOpt == sel_value) {
             return iOptIndex;
         }
     }
     int nOpts = CountOptions();
     for (int i = 0; i < nOpts; i ++) {
@@ skipping 570 matching lines @@
         }
         if (GetType() == ComboBox) {
             m_pForm->m_pFormNotify->AfterValueChange(this);
         }
     }
     m_pForm->m_bUpdated = TRUE;
     return TRUE;
 }
 void CPDF_FormField::LoadDA()
 {
-    CFX_ByteString DA = FPDF_GetFieldAttr(m_pDict, "DA")->GetString();
+    CFX_ByteString DA = FPDF_GetFieldAttr(m_pDict, "DA") ? FPDF_GetFieldAttr(m_pDict, "DA")->GetString() : CFX_ByteString();
     if (DA.IsEmpty()) {
-        DA = m_pForm->m_pFormDict->GetString("DA");
+        DA = m_pForm->m_pFormDict ? m_pForm->m_pFormDict->GetString("DA") : CFX_ByteString();
     }
     if (DA.IsEmpty()) {
         return;
     }
     CPDF_SimpleParser syntax(DA);
     syntax.FindTagParam("Tf", 2);
     CFX_ByteString font_name = syntax.GetWord();
-    CPDF_Dictionary* pFontDict = m_pForm->m_pFormDict->GetDict("DR")->GetDict("Font")->GetDict(font_name);
+    CPDF_Dictionary* pFontDict = NULL;
+    if (m_pForm->m_pFormDict && m_pForm->m_pFormDict->GetDict("DR") &&
+        m_pForm->m_pFormDict->GetDict("DR")->GetDict("Font") )
+    pFontDict = m_pForm->m_pFormDict->GetDict("DR")->GetDict("Font")->GetDict(font_name);
+
     if (pFontDict == NULL) {
         return;
     }
     m_pFont = m_pForm->m_pDocument->LoadFont(pFontDict);
     m_FontSize = FX_atof(syntax.GetWord());
 }