fix DM?

dm/DM.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
@@ skipping 146 matching lines @@
     }
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 static SkTHashSet<SkString> gUninterestingHashes;
 
 static void gather_uninteresting_hashes() {
     if (!FLAGS_uninterestingHashesFile.isEmpty()) {
         SkAutoTUnref<SkData> data(SkData::NewFromFileName(FLAGS_uninterestingHashesFile[0]));
+        if (!data) {
+            SkDebugf("WARNING: unable to read uninteresting hashes from %s\n",
+                     FLAGS_uninterestingHashesFile[0]);
+            return;
+        }
         SkTArray<SkString> hashes;
         SkStrSplit((const char*)data->data(), "\n", &hashes);
         for (const SkString& hash : hashes) {
             gUninterestingHashes.add(hash);
         }
     }
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
@@ skipping 917 matching lines @@
     }
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif