The following error occurred twice on the web version when I was caught by a Fox Jailer while bound by a different Fox Jailer:
An error occurred running the Unity content on this page. See your browser JavaScript console for more info. The error was: RuntimeError: indirect call to null @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[86878]:0x187d2a2 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[86773]:0x1876234 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[86780]:0x1876b68 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[91388]:0x19a4e9d @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[94473]:0x19e7bae @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[119824]:0x268de33 invoke_iiii@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:432007 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[94458]:0x19e724d @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[1633]:0x127a8b @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[115985]:0x25b3589 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[98916]:0x1c19274 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[112559]:0x23b1bd9 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[115508]:0x255f4c8 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[115521]:0x255f97f @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[107668]:0x213c637 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[107860]:0x2153f5b @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[107859]:0x2152da1 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[107857]:0x2152ca4 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[115451]:0x255c4c7 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[115451]:0x255c53c @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[119572]:0x265e181 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[119825]:0x268de3b unityFramework/_JS_CallAsLongAsNoExceptionsSeen/<@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:23468 _JS_CallAsLongAsNoExceptionsSeen@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:23482 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[119573]:0x265e296 @https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.wasm.br:wasm-function[119825]:0x268de3b browserIterationFunc@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:115593 callUserCallback@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:97955 runIter@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:99338 Browser_mainLoop_runner@https://html-classic.itch.zone/html/17152722/WebGL/Build/WebGL.framework.js.br:9:115119
Not sure if all of the details were exactly the same both times, but a message popped up with a similar message after both times it occurred, so I copied the contents the second time so I could provide it here.