src/core/sched_ctx.c: make sure sched_ctx is valid

src/core/sched_ctx.c

@@ -1113,9 +1113,10 @@ static void _starpu_delete_sched_ctx(struct _starpu_sched_ctx *sched_ctx)
 void starpu_sched_ctx_delete(unsigned sched_ctx_id)
 {
 	struct _starpu_sched_ctx *sched_ctx = _starpu_get_sched_ctx_struct(sched_ctx_id);
+	STARPU_ASSERT(sched_ctx);
+
 #ifdef STARPU_USE_SC_HYPERVISOR
-	if(sched_ctx != NULL && sched_ctx_id != 0 && sched_ctx_id != STARPU_NMAX_SCHED_CTXS
-	   && sched_ctx->perf_counters != NULL)
+	if (sched_ctx_id != 0 && sched_ctx_id != STARPU_NMAX_SCHED_CTXS && sched_ctx->perf_counters != NULL)
 	{
 		_STARPU_TRACE_HYPERVISOR_BEGIN();
 		sched_ctx->perf_counters->notify_delete_context(sched_ctx_id);