next_process() checks if a next process exists

Panics if not

src/kernel.c

@@ -73,9 +73,13 @@ struct process_state_t *next_process(struct kernel_t *kernel, struct process_sta
         queue_insert(kernel->priority_queue, kernel->active_process);
     }
     kernel->active_process = extract_min(kernel->priority_queue);
+    if(kernel->active_process != NULL)
+    {
         load_address_space(kernel->active_process->page_table);
         load_context(kernel->active_process->state);
     }
+    panic("no processes available to enter!");
+}
 
 void panic(const char *message)
 {