NullReferenceException: Object reference not set to an instance of an object

[hollow junco]

https://pastebin.com/QHcwZZBf

I am getting this error and I suspect its because 'slot' isn't defined in my script.

NullReferenceException: Object reference not set to an instance of an object
puzzlepiece.OnMouseUp () (at Assets/scripts/puzzlepiece.cs:59)
UnityEngine.SendMouseEvents:DoSendMouseEvents(Int32)

No crashes, game runs fine except for this.

How do I get the engine to recognize the 'slot' object so the code will run? Using a 2D collider on the slot, btw

[hollow junco]

what do you mean?

[wispy tundra]

The error is in puzzlepiece. I'm guessing Vivvy didn't bother scrolling through the pastebin and he didn't notice the class was in there.

If you check the stacktrace, you will notice the last step was in that script, and it's something about a mouse event.

What exactly is line 59 of puzzlepiece @hollow junco ?

I can't figure it out with the pastebin

[hollow junco]

Oh okay!

[hollow junco]

Line 59 is supposed to be inferring the distance between the point of the puzzle piece and the slot it is supposed to be in (colliders).

If the distance between them is less than 2, the piece snaps into place and the game is 'won'

Now I'm not sure how to get the engine to recognize the slot position

It doesn't

[turbid sentinel]

Assuming line 59, in your code file is if (Vector2.Distance(transform.position, slot.transform.position) < 2)

"slot" is not a GameObject, youve defined it as a class (which from the looks of it, doesnt seem like you populate or initialize), what exactly are you trying to access? What is "slot" supposed to be?

[wispy tundra]

So it's if (Vector2.Distance(transform.position, slot.transform.position) < 2)?

Then slot is null

Judging by the code, I see a private field for slot, but no assignment. You also didn't do this through the inspector because it's a private unserialized field

So my guess is you forgot to initialize it

For next time, you can tell by the stacktrace where it went wrong, and you can start debugging your issue. In your case slot was the only variable that could be null, so you could put Debug.Log(slot) above line 59 to check it.

If slot is able to be null, you should change your code to if (Vector2.Distance(transform.position, slot?.transform.position) < 2) (not the question mark). It will then short circuit and stop checking, and the if-statement will fail, of course.

[hollow junco]

slot is a gameobject with a collider that the puzzlepiece will come into contact with. once that happens, the game registers as 'won'

[hollow junco]

thanks! slot should not be null in this case. it should be assigned to a box collider 2D

I found the private slot field and assigned it, but the error still appears

https://pastebin.com/ZLURaUsP

Also added slot.GameObject instead of just 'slot'

[wispy tundra]

This field is called Slot Parent, so I expect it to be called _slotParent / slotParent in the code, but I only see slot

Is this old code, or did you make a mistake?

[wispy tundra]

Note that this code still has a private puzzleslot slot field that has no indication of it being assigned, which would mean that it is null

[hollow junco]

sorry, its an outdated ss

the current ss says 'slot'

my bad

slot = GameObject.Find("slot");

Like this?

Cannot implicitly convert type 'UnityEngine.GameObject' to 'puzzleslot' [Assembly-CSharp]csharp(CS0029)

I get this error in return tho

[wispy tundra]

That's a new error. It indicates that you're trying to use a variable under a specific type, but it is of a type that is not related to it, and there is no valid conversion that exists

In this case, type GameObject that tries to become a puzzleslot

GameObject.Find returns a GameObject.
I assume you have a puzzleslot component on the GameObject that is retrieved.
You basically need to get that component from the GameObject, by doing slot = GameObject.Find("slot").GetComponent<puzzleslot>();

[hollow junco]

yep

[wispy tundra]

However, this is not a good idea. GameObject.Find is slow and both it and GetComponent can return null

[hollow junco]

i see

i didnt know that haha

now i know

[wispy tundra]

What happened to the assignment in the inspector? Why don't you use that?

There does not seem to be a need for that line

[hollow junco]

i tried

still getting the null error

[wispy tundra]

Share the code please

And the new error

So the code without the find and the null error

[hollow junco]

sure thing

NullReferenceException: Object reference not set to an instance of an object
puzzlepiece.OnMouseUp () (at Assets/scripts/puzzlepiece.cs:61)
UnityEngine.SendMouseEvents:DoSendMouseEvents(Int32)

https://pastebin.com/wtkAJ0eM

[wispy tundra]

What is line 61 referring to?

[hollow junco]

if (Vector2.Distance(transform.position, slot.gameObject.transform.position) < 2)

I think its to do with slot not being a gameobject again

but im not 100% certain

[wispy tundra]

This code has the exact same problem, a private field that is unassigned

[wispy tundra]

I'm seeing no trace of it being assigned in the inspector like you showed here

[hollow junco]

huh weird, i assigned it in the inspector

i wonder whats causing it

[wispy tundra]

This is completely different code to, because this is the puzzlepiece class, and the picture shows a puzzleslot

So the thing that you assign is not the slot that throws the error

You seem to confuse yourself by your own code 😛

[hollow junco]

ohhh

let me try to assign it to the proper code

slot.gameObject.transform.position

This one still brings up the error when assigned 😦

It works

okay i just had to set the value 2 much higher

[wispy tundra]

Not sure what you mean

[hollow junco]

The float value attached to the code that compares the distances

turns out it was too small

[wispy tundra]

Right

Your issue is now fixed, right?