Fix exception when no average loudness set

If the average loudness in Engine Library format is zero, this is now
interpreted as there being no average loudness.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/djinterop/enginelibrary/el_track_impl.cpp b/src/djinterop/enginelibrary/el_track_impl.cpp
index 707253e..0febf3b 100644
--- a/src/djinterop/enginelibrary/el_track_impl.cpp
+++ b/src/djinterop/enginelibrary/el_track_impl.cpp
@@ -317,7 +317,11 @@ void el_track_impl::set_average_loudness(
 {
     el_transaction_guard_impl trans{storage_};
     auto track_d = get_track_data();
-    track_d.average_loudness = average_loudness;
+
+    // Zero average loudness is interpreted as no average loudness.
+    track_d.average_loudness =
+        average_loudness == 0 ? stdx::nullopt : average_loudness;
+
     set_track_data(track_d);
     trans.commit();
 }