[Bug] Screen freezes after delete targeted token

[devnagui]

Steps to reproduce:

1. Target some token
   

2. Delete targeted token

Stacktrace:
Graphics.ts:934 Uncaught (in promise) TypeError: Cannot read property 'clear' of null
at r.clear (Graphics.ts:934)
at controlTokenEventHandler (target-enhancements.js:436)
r.clear @ Graphics.ts:934
controlTokenEventHandler @ target-enhancements.js:436
async function (async)
controlTokenEventHandler @ target-enhancements.js:408
_call @ foundry.js:2496
callAll @ foundry.js:2456
release @ foundry.js:11616
_onDelete @ foundry.js:11545
_onDelete @ foundry.js:45027
_onDeleteEmbeddedEntity @ foundry.js:34169
(anonymous) @ foundry.js:30073
(anonymous) @ target-enhancements.js:25
Array.partition @ target-enhancements.js:24
_handleDeleteEmbeddedEntity @ foundry.js:30071
_handleDeleteEmbeddedEntity @ foundry.js:34220
deleteEmbeddedEntity @ foundry.js:30048
async function (async)
deleteEmbeddedEntity @ foundry.js:30038
deleteMany @ foundry.js:12419
_onDeleteKey @ foundry.js:12735
_onDelete @ foundry.js:3233
_handleKeys @ foundry.js:2807
_onKeyDown @ foundry.js:2760
DisplayObject.ts:673 Uncaught TypeError: Cannot read property 'scale' of null
at e.get (DisplayObject.ts:673)
at t.fn (TargetIndicator.js:233)
at t.emit (TickerListener.ts:109)
at e.update (Ticker.ts:505)
at _tick (Ticker.ts:189)

[nationwide13]

Wrote a quick PR to fix this issue. Not the most familiar with Foundry/PixiJS, so it might not be the most optimal solution. #28