fix crashes when files fail to open

stepmania/src/RageSoundReader_MP3.cpp

@@ -689,7 +689,11 @@ SoundReader_FileReader::OpenResult RageSoundReader_MP3::Open( CString filename_
 {
 	filename = filename_;
     rw = fopen(filename, "rb");
-	ASSERT( rw );
+	if( !rw )
+	{
+		SetError( ssprintf("Couldn't open file: %s", strerror(errno)) );
+		return OPEN_NO_MATCH;
+	}
 
 	int ret = fseek( this->rw, 0, SEEK_END );
 	ASSERT( ret != -1 );

stepmania/src/RageSoundReader_Vorbisfile.cpp

@@ -70,7 +70,7 @@ SoundReader_FileReader::OpenResult RageSoundReader_Vorbisfile::Open(CString file
 	if(f == NULL)
 	{
 		SetError(ssprintf("ogg fopen(%s) failed: %s", filename.c_str(), strerror(errno)));
-		return OPEN_MATCH_BUT_FAIL;
+		return OPEN_NO_MATCH;
 	}
 
 	int ret = ov_open(f, vf, NULL, 0);
@@ -208,6 +208,11 @@ int RageSoundReader_Vorbisfile::GetSampleRate() const
 	return vi->rate;
 }
 
+RageSoundReader_Vorbisfile::RageSoundReader_Vorbisfile()
+{
+	vf = NULL;
+}
+
 RageSoundReader_Vorbisfile::~RageSoundReader_Vorbisfile()
 {
 	if(vf)

stepmania/src/RageSoundReader_Vorbisfile.h

@@ -21,6 +21,7 @@ public:
 	int SetPosition_Fast(int ms) { return SetPosition(ms, false); }
 	int Read(char *buf, unsigned len);
 	int GetSampleRate() const;
+	RageSoundReader_Vorbisfile();
 	~RageSoundReader_Vorbisfile();
 	SoundReader *Copy() const;
 };

stepmania/src/RageSoundReader_WAV.cpp

@@ -511,6 +511,11 @@ SoundReader_FileReader::OpenResult RageSoundReader_WAV::Open( CString filename_
 	Input_Buffer_Ratio = 1;
 	filename = filename_;
     rw = fopen(filename, "rb");
+	if( !rw )
+	{
+		SetError( ssprintf("Couldn't open file: %s", strerror(errno)) );
+		return OPEN_NO_MATCH;
+	}
 
     memset(&fmt, 0, sizeof(fmt));