This bug cause a false assert due to multiple threads modifying the same variable without any atomic operation.

Bug lines:
SDL_android.c
static int s_active = 0;
...
static SDL_bool LocalReferenceHolder_Init(struct LocalReferenceHolder *refholder, JNIEnv *env)
{
    const int capacity = 16;
    if ((*env)->PushLocalFrame(env, capacity) < 0) {
        SDL_SetError("Failed to allocate enough JVM local references");
        return SDL_FALSE;
    }
    ++s_active;
    refholder->m_env = env;
    return SDL_TRUE;
}
...
static void LocalReferenceHolder_Cleanup(struct LocalReferenceHolder *refholder)
{
#ifdef DEBUG_JNI
    SDL_Log("Leaving function %s", refholder->m_func);
#endif
    if (refholder->m_env) {
        JNIEnv* env = refholder->m_env;
		(*env)->PopLocalFrame(env, NULL);
		--s_active;
    }
}
...
static SDL_bool LocalReferenceHolder_IsActive(void)
{
    return s_active > 0;
}

Solution:
static SDL_atomic_t s_active = { 0 };
...
static SDL_bool LocalReferenceHolder_Init(struct LocalReferenceHolder *refholder, JNIEnv *env)
{
    const int capacity = 16;
    if ((*env)->PushLocalFrame(env, capacity) < 0) {
        SDL_SetError("Failed to allocate enough JVM local references");
        return SDL_FALSE;
    }
	SDL_AtomicIncRef(&s_active);
    refholder->m_env = env;
    return SDL_TRUE;
}
...
static void LocalReferenceHolder_Cleanup(struct LocalReferenceHolder *refholder)
{
#ifdef DEBUG_JNI
    SDL_Log("Leaving function %s", refholder->m_func);
#endif
    if (refholder->m_env) {
        JNIEnv* env = refholder->m_env;
		(*env)->PopLocalFrame(env, NULL);
		SDL_AtomicDecRef(&s_active);
    }
}
...
static SDL_bool LocalReferenceHolder_IsActive(void)
{
    return SDL_AtomicGet(&s_active) > 0;
}

Extra bug lines:
In some branches and [default] there is a line modified to use directly s_active, and should instead use LocalReferenceHolder_IsActive.

SDL_assert((s_active > 0));

Solution:
SDL_assert(LocalReferenceHolder_IsActive());