Self Pointer Ambiguous Context Crash(Now a Zero-Address)

[Silentdarkness12]

I'm having a bit of trouble with making an addon for Hideous Destructor to add a shield to the arsenal.

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Class CGIUsable : HDPickup
{
Default
{
+COUNTITEM;
+INVENTORY.INVBAR;
  Inventory.MaxAmount 1;
  Inventory.Icon "SEPSA0";
  hdpickup.bulk 80;
  Inventory.PickupMessage "Picked up a Cover Generation Initializer.";
}
int shieldid;
int loadcell;
States
{
Spawn:
    SEPS A 1;
	SEPS A 1;
    Loop;
  Use:
  TNT1 A 1{
  let bbb=HDMagAmmo(findinventory("HDBattery"));
  if(!bbb){
  A_Log("\cd[CGI]\cj  No power. Please load 1 cell pack before deploying.",true);
  return;
  }else{
				loadcell=invoker.bbb.TakeMag(true);
			}
  }
TNT1 A 1{
	A_SpawnItemEx ("CGIActive", 56, 0, 8, 0, 0, 0, 0, SXF_NOCHECKPOSITION|SXF_TRANSFERTRANSLATION|SXF_TRANSFERPOINTERS|SXF_SETMASTER);
	actor sss; int iii;
  let SSSS=CGIActive(SSS);
  SSSS.battery=loadcell;
  SSSS.shieldid=invoker.shieldid;
	invoker.goawayanddie();
	} 
    Stop;
}
}

Getting 2 "Self Pointer is used in an ambiguous context" errors in this, on these lines:

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loadcell=invoker.bbb.TakeMag(true);

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 SSSS.battery=loadcell;

[Blue Shadow]

'loadcell' is a variable of the item itself (invoker), so try changing those lines to this:

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invoker.loadcell=bbb.TakeMag(true);

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 SSSS.battery=invoker.loadcell;

[Silentdarkness12]

Many thanks. It's good now.

[Silentdarkness12]

Actually, wait, no. It's not. New game and it crashes. Write to Address Zero crash.

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VM execution aborted: tried to write to address zero.
Called from CGIUsable.StateFunction.3 at HDShield.pk3:zscript, line 722
Called from state CGIUsable.3 in inventory state chain in CGIUsable
Called from CustomInventory.CallStateChain [Native]
Called from CustomInventory.Use at gzdoom.pk3:zscript/inventory/stateprovider.txt, line 95

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SSSS.battery=invoker.loadcell;

[phantombeta]

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A_SpawnItemEx ("CGIActive", 56, 0, 8, 0, 0, 0, 0, SXF_NOCHECKPOSITION|SXF_TRANSFERTRANSLATION|SXF_TRANSFERPOINTERS|SXF_SETMASTER);
   actor sss; int iii;

You never set sss, so it's always null. Now, what I think you wanted to do here was

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bool spawned; actor sss;
[spawned, sss] = A_SpawnItemEx ("CGIActive", 56, 0, 8, 0, 0, 0, 0, SXF_NOCHECKPOSITION|SXF_TRANSFERTRANSLATION|SXF_TRANSFERPOINTERS|SXF_SETMASTER);

After this, you have to check if spawned is true and sss isn't null.
Yes, you need to check both. For some reason it doesn't return null if it failed to spawn.

Also, you really should use descriptive variable names and proper indentation. Bad indentation and variable names means it's harder for others to help, specially when the indentation is really bad, or even non-existent.
As an example, I wanted to try to help fix the MP issues in HD, but with the bad indentation and unclear, confusing variable names, I gave up due to how unreadable HD's source code is.

[Graf Zahl]

Yes, you need to check both. For some reason it doesn't return null if it failed to spawn.

That "some reason" is one special situation: Imagine you spawned something that immediately got destroyed, but still need to perform some action with that actor. In that case you both need the pointer and a success value. One of the internal weapons needs this, I can't remember right now which one.

[phantombeta]

I should probably have specified - the pointer is non-null, but it's already freed by the time A_SpawnItemEx returns. Accessing the pointer crashes the game with a fatal error.
I'd make a report for it, but my computer's dead, so I can't really do that.

[Graf Zahl]

It cannot be freed. The garbage collector shouldn't kick in at that point, it only runs after a frame has ended. If it crashes on the pointer it must be bogus.