[BUG] Paywall preloading hangs main thread and crashes WebContent on iOS 26

[georgecartridge]

New issue checklist

• I have reviewed the README and documentation
• I have searched existing issues and this is not a duplicate
• I have attempted to reproduce the issue and include an example project.

General information

• Superwall version: 4.14.2
• iOS version(s): 26.1 / 26.3.1 / 26.4.1
• Xcode version: 26.1
• Devices/Simulators affected: iPhone 13 (Physical) / iPhone 15 Plus (Physical) / iPhone 12 (Simulator)

Describe the bug

We're calling Superwall.configure(apiKey:) on app launch with default options - no custom SuperwallOptions, no overrides, just the standard configuration as documented in the setup guide. All of the paywalls are being preloaded.

On iOS 26.1 (simulator) / 26.3.1 (physical device) / 26.4.1 (physical device) , this preload phase is causing visible app freezes for the user during launch. Instruments confirms a Brief Unresponsiveness hang of ~188 ms about 8 seconds into launch.

When the preload kicks in, the Xcode console fills with output like this (truncated - there are 180+ of these):

WebContent[36963] Unable to hide query parameters from script (missing data)
WebContent[36965] Unable to hide query parameters from script (missing data)
...

WebContent[36963] makeImagePlus:3798: *** ERROR: 'WEBP'-_reader->initImage[0] failed err=-50
WebContent[36963] makeImagePlus:3798: *** ERROR: 'WEBP'-_reader->initImage[0] failed err=-50
... (repeats ~15 times for PID 36963) ...

WebContent[36965] makeImagePlus:3798: *** ERROR: 'WEBP'-_reader->initImage[0] failed err=-50
WebContent[36965] makeImagePlus:3798: *** ERROR: 'WEBP'-_reader->initImage[0] failed err=-50
... (repeats ~15 times for PID 36965) ...

WebContent[36963] 0x10d04c100 - [sessionID=1] WebProcess::updateFreezerStatus: isFreezable=1, error=-1
WebContent[36965] 0x10d04c100 - [sessionID=1] WebProcess::updateFreezerStatus: isFreezable=1, error=-1
WebContent[36966] 0x11004c100 - [sessionID=1] WebProcess::updateFreezerStatus: isFreezable=1, error=-1
WebContent[36967] 0x11104c100 - [sessionID=1] WebProcess::updateFreezerStatus: isFreezable=1, error=-1
WebContent[36960] 0x11004c100 - [sessionID=1] WebProcess::updateFreezerStatus: isFreezable=1, error=-1

0x130088680 - [PID=36963] WebProcessProxy::didClose: (web process 0 crash)
0x130088680 - [PID=36963] WebProcessProxy::processDidTerminateOrFailedToLaunch: reason=Crash
0x130088c40 - [PID=36965] WebProcessProxy::didClose: (web process 0 crash)
0x130089200 - [PID=36966] WebProcessProxy::didClose: (web process 0 crash)
0x1300897c0 - [PID=36967] WebProcessProxy::didClose: (web process 0 crash)
0x1300880c0 - [PID=36960] WebProcessProxy::didClose: (web process 0 crash)

When tested on iOS 18.2, these errors do not appear in the console and the app no longer freezes.
On iOS 26.x, if I disable paywall preloading – paywalls.shouldPreload = false – then the app no longer freezes. However, once a paywall appears, the console shows output like the above (but a smaller amount)

Whilst I see all of these errors and freezes, the app still renders the paywalls. There's no missing images or assets

[linear]

SW-5244