- make file-tool example more robust

examples/iec61850_client_example_files/file-tool.c

@@ -101,13 +101,14 @@ downloadHandler(void* parameter, uint8_t* buffer, uint32_t bytesRead)
 
     printf("received %i bytes\n", bytesRead);
 
+    if (bytesRead > 0) {
         if (fwrite(buffer, bytesRead, 1, fp) == 1)
             return true;
         else {
             printf("Failed to write local file!\n");
             return false;
         }
-
+    }
 }
 
 static void