From b81e5c8f3e1f94a0d059874d4edb5e934dedf0a1 Mon Sep 17 00:00:00 2001
From: Nicolas Hug <nicolashug@meta.com>
Date: Fri, 5 Sep 2025 21:37:49 +0100
Subject: [PATCH] Assert deviceInterface_ exists when it should

---
 src/torchcodec/_core/SingleStreamDecoder.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/torchcodec/_core/SingleStreamDecoder.cpp b/src/torchcodec/_core/SingleStreamDecoder.cpp
index 865179a18..864e82d0a 100644
--- a/src/torchcodec/_core/SingleStreamDecoder.cpp
+++ b/src/torchcodec/_core/SingleStreamDecoder.cpp
@@ -1246,7 +1246,11 @@ FrameOutput SingleStreamDecoder::convertAVFrameToFrameOutput(
       formatContext_->streams[activeStreamIndex_]->time_base);
   if (streamInfo.avMediaType == AVMEDIA_TYPE_AUDIO) {
     convertAudioAVFrameToFrameOutputOnCPU(avFrame, frameOutput);
-  } else if (deviceInterface_) {
+  } else {
+    TORCH_CHECK(
+        deviceInterface_ != nullptr,
+        "No device interface available for video decoding. This ",
+        "shouldn't happen, please report.");
     deviceInterface_->convertAVFrameToFrameOutput(
         streamInfo.videoStreamOptions,
         streamInfo.timeBase,