FIX: Don't SEGV when not selecting any file with OpenAudioFile

src/AudioUtils.c

@@ -9,7 +9,7 @@
 #define MAXPIXVALUE 7 /* Some magix AV magic stuff */
 
 int
-decode_audio_file(const char *path, const int sample_rate, double **const data, int *const size)
+decodeAudioFile(const char *path, const int sample_rate, double **const data, int *const size)
 {
     AVPacket packet;
     AVFormatContext *format      = avformat_alloc_context();

src/AudioUtils.h

@@ -7,7 +7,7 @@ extern "C" {
 
 #include <libavcodec/avcodec.h>
 
-int decode_audio_file(const char *path, const int sample_rate, double **const data, int *const size);
+int decodeAudioFile(const char *path, const int sample_rate, double **const data, int *const size);
 
 typedef struct ___RawImageData RawImageData;
 RawImageData *RawImageDataNewFromData(const double *data, const int size);

src/MainWindow.cc

@@ -35,11 +35,13 @@ void
 MainWindow::openAudioFile()
 {
     QString filename = QFileDialog::getOpenFileName(this, "Select a file");
+    if (filename.isEmpty())
+        return;
 
     const int sample_rate = 44100;
     double *data          = nullptr;
     int size              = 0;
-    int rc                = decode_audio_file(filename.toStdString().c_str(), sample_rate, &data, &size);
+    int rc                = decodeAudioFile(filename.toStdString().c_str(), sample_rate, &data, &size);
     auto data_deleter     = [](double *ptr) -> void { av_free(ptr); };
     std::unique_ptr<double, decltype(data_deleter)> data_holder(data, data_deleter);