Crash switching to Polygon in Swap

[StephenHeaps]

Description:

Crash when switching to Polygon in native Swap after change to use WebImageDownloader from core.

Steps to Reproduce

Swap:

1. Open Swap
2. Change network to Polygon
3. Crash

Edit User Assets:

1. Open Portfolio and tap Edit User Assets button beside filters button
2. Optional: Change network filter to only have Polygon network selected
3. Scroll down list until crashes

Actual result:

Crashes

Expected result:

Does not crash

Reproduces how often:

Easily reproduced

Brave Version:

v1.57+

• Can you reproduce this issue with the most recent build from TestFlight?
• Can you reproduce this issue with the previous version of the current build from TestFlight?
• Can you reproduce this issue with the current build from AppStore?

Device details:

Website problems only:

• did you check with Brave Shields down?
• did you check in Safari/Firefox (WkWebView-based browsers)?

Additional Information

[srirambv]

Verification passed on the following devices running 1.57 (23.8.24.22)

• Verified steps from #7908
• Verified no crash when selecting Polygon on Swap screen
• Verified no crash when filtering tokens to Polygon network in edit visible asset screen
• Encountered #7961

iPhone 7+ (iOS 15.7.8)	iPhone 13 (iOS 16.6)	iPad Pro (iOS 16.6)
7907-iPhone.7+.MP4	7907-iPhone.13.MP4	7907-iPad.Pro.MP4