fix: crash when processing audio

.gitmodules

@@ -1,6 +1,7 @@
 [submodule "ext/core"]
 	path = ext/core
 	url = https://github.com/OliveCommunity/core.git
+	branch = dev
 [submodule "ext/KDDockWidgets"]
 	path = ext/KDDockWidgets
 	url = https://github.com/olive-editor/KDDockWidgets.git

app/codec/ffmpeg/ffmpegdecoder.cpp

@@ -629,7 +629,7 @@ bool FFmpegDecoder::ConformAudioInternal(const QVector<QString> &filenames,
 	}
 	// Create resampling context
 	AVChannelLayout layout = params.channel_layout();
-	SwrContext *resampler;
+	SwrContext *resampler=NULL;
 	swr_alloc_set_opts2(
 		&resampler, &layout,
 		FFmpegUtils::GetFFmpegSampleFormat(params.format()),