Fix crash on diskcache purge

indra/llfilesystem/lldiskcache.cpp

@@ -113,7 +113,10 @@ void LLDiskCache::purge()
 #endif
     if (boost::filesystem::is_directory(cache_path, ec) && !ec.failed())
     {
-        for (auto& entry : boost::make_iterator_range(boost::filesystem::recursive_directory_iterator(cache_path), {}))
+        boost::filesystem::recursive_directory_iterator dir_iter(cache_path, ec);
+        if (!ec.failed())
+        {
+            for (auto& entry : boost::make_iterator_range(dir_iter, {}))
             {
                 ec.clear();
                 if (boost::filesystem::is_regular_file(entry, ec) && !ec.failed())
@@ -138,6 +141,7 @@ void LLDiskCache::purge()
                 }
             }
         }
+    }
 
     std::sort(file_info.begin(), file_info.end(), [](const file_info_t& x, const file_info_t& y)
     {
@@ -176,6 +180,7 @@ void LLDiskCache::purge()
                 if (ec.failed())
                 {
                     LL_WARNS() << "Failed to delete cache file " << entry.second.second << ": " << ec.message() << LL_ENDL;
+                    continue;
                 }
             }
         }
@@ -414,7 +419,10 @@ uintmax_t LLDiskCache::dirFileSize(const std::string dir)
 #endif
     if (boost::filesystem::is_directory(dir_path, ec) && !ec.failed())
     {
-        for (auto& entry : boost::make_iterator_range(boost::filesystem::recursive_directory_iterator(dir_path), {}))
+        boost::filesystem::recursive_directory_iterator dir_iter(dir_path,ec);
+        if (!ec.failed())
+        {
+            for (auto& entry : boost::make_iterator_range(dir_iter, {}))
             {
                 ec.clear();
                 if (boost::filesystem::is_regular_file(entry, ec) && !ec.failed())
@@ -432,6 +440,7 @@ uintmax_t LLDiskCache::dirFileSize(const std::string dir)
                 }
             }
         }
+    }
 
     return total_file_size;
 }