fox32os: Don't mark task 0 as unused when yielding for the first time

kernel/main.asm

@@ -84,8 +84,9 @@ draw_startup_text:
 
     ; when the startup file yields for the first time, we'll end up back here
     ; jump back to it without adding this "task" (not really a task) into the queue
+    ; end_current_task_no_mark is used specifically because it doesn't mark the current task (still set to 0) as unused
     ; this does not return
-    call end_current_task
+    call end_current_task_no_mark
 
 startup_error:
     mov r0, BACKGROUND_COLOR

kernel/task.asm

@@ -43,13 +43,14 @@ yield_task:
 ; outputs:
 ; none
 end_current_task:
-    cmp [task_queue_ptr], task_queue_bottom
-    ifz jmp task_empty
-
     mov r0, current_task ; get the current task struct
     call task_load
     bcl [task_id_bitmap], r2 ; mark this task ID as unused
+end_current_task_no_mark:
     pop r0 ; pop the return address off of the stack
+
+    cmp [task_queue_ptr], task_queue_bottom
+    ifz jmp task_empty
 yield_task_0:
     mov r0, task_queue_bottom
     call task_load