I added audio errors

The only thing I did not change was the _g for globals. Is there any
other way we can mark globals?

src/audio.h

@@ -47,10 +47,29 @@
     #endif
 #endif
 
+typedef enum {
+    ERROR_RAW_CONTEXT_CREATION = -20,
+    ERROR_XM_CONTEXT_CREATION,
+    ERROR_MOD_CONTEXT_CREATION,
+    ERROR_MIX_CHANNEL_CREATION,
+    ERROR_MUSIC_CHANNEL_CREATION,
+    ERROR_LOADING_XM,
+    ERROR_LOADING_MOD,
+    ERROR_LOADING_WAV,
+    ERROR_LOADING_OGG,
+    ERROR_OUT_OF_MIX_CHANNELS,
+    ERROR_EXTENSION_NOT_RECOGNIZED,
+    ERROR_UNABLE_TO_OPEN_RRES_FILE,
+    ERROR_INVALID_RRES_FILE,
+    ERROR_INVALID_RRES_RESOURCE,
+    ERROR_UNINITIALIZED_CHANNELS
+} AudioError;
+
 // Sound source type
 typedef struct Sound {
     unsigned int source;
     unsigned int buffer;
+    AudioError error; // if there was any error during the creation or use of this Sound
 } Sound;
 
 // Wave type, defines audio wave data
@@ -64,6 +83,7 @@ typedef struct Wave {
 
 typedef int RawAudioContext;
 
+
 #ifdef __cplusplus
 extern "C" {            // Prevents name mangling of functions
 #endif