Fix undeclared initialSyncDepth

[ymeister]

Using haskell.nix on GHC 9.14

Uncaught (in promise) ReferenceError: initialSyncDepth is not defined
    at ghc_wasm_jsffi.js:391:20
(anonymous) @ ghc_wasm_jsffi.js:391
await in (anonymous)
ZC11ZCjsaddlezmwasmzm0zi1zi2zi1zm4nTggErMHhbGP3scjpvspAZCLanguageziJavascriptziJSaddleziWasmziInternalZC @ ghc_wasm_jsffi.js:395
$ghczuwasmzujsffiZC11ZCjsaddlezmwasmzm0zi1zi2zi1zm4nTggErMHhbGP3scjpvspAZCLanguageziJavascriptziJSaddleziWasmziInternalZC @ frontend.wasm-03f43a16:0x893353
$_blk_cc3b @ frontend.wasm-03f43a16:0x8923bd
$StgRun @ frontend.wasm-03f43a16:0xcb7475
$scheduleWaitThread @ frontend.wasm-03f43a16:0xc961a4
$rts_promiseResolveUnit @ frontend.wasm-03f43a16:0xcb7d64
(anonymous) @ ghc_wasm_jsffi.js:524
Promise.then
ZC18ZCghczminternalZCGHCziInternalziWasmziPrimziImportsZC @ ghc_wasm_jsffi.js:524
$ghczuwasmzujsffiZC18ZCghczminternalZCGHCziInternalziWasmziPrimziImportsZC @ frontend.wasm-03f43a16:0xc84303
$_blk_c1zk @ frontend.wasm-03f43a16:0xc83ff7
$StgRun @ frontend.wasm-03f43a16:0xcb7475
$scheduleWaitThread @ frontend.wasm-03f43a16:0xc961a4
$rts_inCall @ frontend.wasm-03f43a16:0xc8b09f
$hs_start @ frontend.wasm-03f43a16:0x420a8
(anonymous) @ all.js:25
await in (anonymous)
(anonymous) @ all.js:26
(anonymous) @ all.js:27