Assert return value of mutex functions

Mutex functions may only fail due to a programming error.

Use assertions in debug builds, and ignore the value in release builds.

app/src/util/lock.h

@@ -9,44 +9,66 @@
 
 static inline void
 mutex_lock(SDL_mutex *mutex) {
-    if (SDL_LockMutex(mutex)) {
-        LOGC("Could not lock mutex");
+    int r = SDL_LockMutex(mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not lock mutex: %s", SDL_GetError());
         abort();
     }
+#else
+    (void) r;
+#endif
 }
 
 static inline void
 mutex_unlock(SDL_mutex *mutex) {
-    if (SDL_UnlockMutex(mutex)) {
-        LOGC("Could not unlock mutex");
+    int r = SDL_UnlockMutex(mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not unlock mutex: %s", SDL_GetError());
         abort();
     }
+#else
+    (void) r;
+#endif
 }
 
 static inline void
 cond_wait(SDL_cond *cond, SDL_mutex *mutex) {
-    if (SDL_CondWait(cond, mutex)) {
-        LOGC("Could not wait on condition");
+    int r = SDL_CondWait(cond, mutex);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not wait on condition: %s", SDL_GetError());
         abort();
     }
+#else
+    (void) r;
+#endif
 }
 
 static inline int
 cond_wait_timeout(SDL_cond *cond, SDL_mutex *mutex, uint32_t ms) {
     int r = SDL_CondWaitTimeout(cond, mutex, ms);
+#ifndef NDEBUG
     if (r < 0) {
-        LOGC("Could not wait on condition with timeout");
+        LOGC("Could not wait on condition with timeout: %s", SDL_GetError());
         abort();
     }
+#endif
     return r;
 }
 
 static inline void
 cond_signal(SDL_cond *cond) {
-    if (SDL_CondSignal(cond)) {
-        LOGC("Could not signal a condition");
+    int r = SDL_CondSignal(cond);
+#ifndef NDEBUG
+    if (r) {
+        LOGC("Could not signal a condition: %s", SDL_GetError());
         abort();
     }
+#else
+    (void) r;
+#endif
 }
 
 #endif