Update src/core/others/ojph_file.cpp

Author: hmaarrfk

src/core/others/ojph_file.cpp

@@ -215,7 +215,7 @@ namespace ojph {
 #else
       new_buf = (ui8*)aligned_alloc(4096, needed_size);
 #endif
-      if (this->buf != new_buf && !clear_all){
+      if (this-buf != nullptr && this->buf != new_buf && !clear_all){
         memcpy(new_buf, this->buf, used_size);
 #ifdef OJPH_OS_WINDOWS
         _aligned_free(this->buf);