fix (scheduler): added chunk NULL reference check when resolving processes

kernel/src/proc/scheduler.c

@@ -255,6 +255,9 @@ process_T* scheduler_get_process(pid_t pid) {
     uint32_t index_in_chunk = pid % SCHEDULER_PROCESS_CHUNK_SIZE;
 
     scheduler_processes_chunk_T* chunk = g_scheduler.processes;
+    if (chunk == NULL) {
+        return NULL;
+    }
     for (uint32_t i = 0; i < num_chunks; i++) {
         chunk = chunk->next;