[analyzer] Remove redundant output errs

[nullptr.cpp]

Summary

No need to output errs if already have NDEBUG defined.

[xazax.hun]

LGTM, thanks!

[nullptr.cpp]

I don't have commit access, can you help commit it?

In D86334#2230032, @xazax.hun wrote:

LGTM, thanks!

clang/lib/StaticAnalyzer/Core/ExprEngine.cpp

 
 } // namespace llvm
 #endif
 
 void ExprEngine::ViewGraph(bool trim) {
 #ifndef NDEBUG
   std::string Filename = DumpGraph(trim);
   llvm::DisplayGraph(Filename, false, llvm::GraphProgram::DOT);
-#endif
+#else
   llvm::errs() << "Warning: viewing graph requires assertions" << "\n";
+#endif
 }
 
 
 void ExprEngine::ViewGraph(ArrayRef<const ExplodedNode*> Nodes) {
 #ifndef NDEBUG
   std::string Filename = DumpGraph(Nodes);
   llvm::DisplayGraph(Filename, false, llvm::GraphProgram::DOT);
-#endif
+#else
   llvm::errs() << "Warning: viewing graph requires assertions" << "\n";
+#endif
 }
 
 std::string ExprEngine::DumpGraph(bool trim, StringRef Filename) {
 #ifndef NDEBUG
   if (trim) {
     std::vector<const ExplodedNode *> Src;
 
     // Iterate through the reports and get their nodes.

 
 std::string ExprEngine::DumpGraph(ArrayRef<const ExplodedNode*> Nodes,
                                   StringRef Filename) {
 #ifndef NDEBUG
   std::unique_ptr<ExplodedGraph> TrimmedG(G.trim(Nodes));
 
   if (!TrimmedG.get()) {
     llvm::errs() << "warning: Trimmed ExplodedGraph is empty.\n";
+    return "";
   } else {
     return llvm::WriteGraph(TrimmedG.get(), "TrimmedExprEngine",
                             /*ShortNames=*/false,
                             /*Title=*/"Trimmed Exploded Graph",
                             /*Filename=*/std::string(Filename));
   }
-#endif
+#else
   llvm::errs() << "Warning: dumping graph requires assertions" << "\n";
   return "";
+#endif
 }
 
 void *ProgramStateTrait<ReplayWithoutInlining>::GDMIndex() {
   static int index = 0;
   return &index;
 }
 
 void ExprEngine::anchor() { }