Crash when evaluate_javascript() is called in early stage.

[zlx0000]

Calling evaluate_javascript() very early after starting page loading in the Live2DHandler causes a crash inside WebKitGTK.

It seems to happen when evaluate_javascript() is invoked before the WebView is fully initialized or before the page is fully loaded, but the exact internal cause is not fully confirmed yet.

If the evaluate_javascript() function call is paused (for example with pdb), the crash does not occur and the JavaScript executes correctly.

Steps to Reproduce

1. Launch the application normally. flatpak run moe.nyarchlinux.assistant
2. During initialization, the Live2DHandler creates a WebKitWebView, starts loading a web page, and immediately calls evaluate_javascript().
3. The program receives SIGABRT and crashes automatically during startup without requiring any manual user interaction.

Backtrace

#0 __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44 #1 0x00007ffff769ae23 in __pthread_kill_internal (threadid=<optimized out>, signo=6) at pthread_kill.c:78 #2 0x00007ffff764208e in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26 #3 0x00007ffff7629882 in __GI_abort () at abort.c:79 #4 0x00007fff9432fc6f in WTFCrashWithInfo () at WTF/Headers/wtf/Assertions.h:931 #5 0x00007fff949de205 in WebKit::WebProcessPool::pageEndUsingWebsiteDataStore (this=0x7fff88034130, page=..., dataStore=...) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/WebProcessPool.cpp:1323 #6 0x00007fff949eb0fc in WebKit::WebProcessProxy::removeWebPage (this=0x7fff8a000600, webPage=..., endsUsingDataStore=WebKit::WebProcessProxy::EndsUsingDataStore::Yes) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/WebProcessProxy.cpp:909 #7 0x00007fff94966105 in WebKit::WebPageProxy::launchProcess (this=0x7fff8a000c00, site=..., reason=WebKit::WebPageProxy::ProcessLaunchReason::InitialProcess) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/WebPageProxy.cpp:1317 #8 0x00007fff94972815 in WebKit::WebPageProxy::launchInitialProcessIfNecessary (this=0x7fff8a000c00) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/WebPageProxy.cpp:6157 #9 0x00007fff9497cae6 in WebKit::WebPageProxy::runJavaScriptInFrameInScriptWorld (this=0xe, parameters=..., frameID=std::optional [no contained value], world=..., callbackFunction=...) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/WebPageProxy.cpp:6168 #10 0x00007fff94a7058a in webkitWebViewRunJavaScriptWithParams (webView=webView@entry=0x555556e0dfd0 [WebKitWebView], params=..., worldName=worldName@entry=0x0, returnType=RunJavascriptReturnType::JSCValue, task=...) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp:4180 #11 0x00007fff94a7085f in webkitWebViewEvaluateJavascriptInternal (returnType=RunJavascriptReturnType::JSCValue, callback=0x7ffff6eace88, userData=0x7fffa4004e90, webView=<optimized out>, script=<optimized out>, length=<optimized out>, worldName=<optimized out>, sourceURI=<optimized out>, cancellable=<optimized out>) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp:4239 #12 webkit_web_view_evaluate_javascript (webView=0x555556e0dfd0 [WebKitWebView], script=<optimized out>, length=<optimized out>, worldName=0x0, sourceURI=0x0, cancellable=0x0, callback=0x7ffff6eace88, userData=0x7fffa4004e90) at /buildstream/gnome/sdk/webkitgtk-6.0.bst/Source/WebKit/UIProcess/API/glib/WebKitWebView.cpp:4312 #13 0x00007ffff6f89056 in ffi_call_unix64 () at ../src/x86/unix64.S:104 #14 0x00007ffff6f87e0e in ffi_call_int (cif=cif@entry=0x7fffa40051d0, fn=<optimized out>, rvalue=<optimized out>, avalue=<optimized out>, closure=closure@entry=0x0) at ../src/x86/ffi64.c:676 #15 0x00007ffff6f8864e in ffi_call (cif=cif@entry=0x7fffa40051d0, fn=<optimized out>, rvalue=rvalue@entry=0x7fffafffeae8, avalue=<optimized out>) at ../src/x86/ffi64.c:713 #16 0x00007ffff71de245 in pygi_invoke_c_callable (function_cache=<optimized out>, state=<optimized out>, py_args=<optimized out>, py_nargsf=<optimized out>, py_kwnames=<optimized out>) at ../gi/pygi-invoke.c:710 #17 0x00007ffff71e0774 in pygi_function_cache_invoke (function_cache=<optimized out>, py_args=<optimized out>, py_nargsf=<optimized out>, py_kwnames=<optimized out>) at ../gi/pygi-cache.c:951 #18 0x00007ffff796e8bc in _PyObject_VectorcallTstate (tstate=0x7fff24008940, callable=0x7fffc56f5b90, args=0x7fffe03ab2f0, nargsf=9223372036854775811, kwnames=0x7fffe1f95690) at ../Include/internal/pycore_call.h:92 #19 PyObject_Vectorcall (callable=callable@entry=0x7fffc56f5b90, args=args@entry=0x7fffe03ab2f0, nargsf=9223372036854775811, kwnames=kwnames@entry=0x7fffe1f95690) at ../Objects/call.c:325 #20 0x00007ffff7b6fdec in _PyEval_EvalFrameDefault (tstate=<optimized out>, frame=0x7fffe03ab280, throwflag=<optimized out>) at Python/bytecodes.c:2715 #21 0x00007ffff7b5496a in _PyObject_VectorcallTstate (tstate=0x7fff24008940, callable=0x7ffff73b6340, args=0x7fffafffee08, nargsf=1, kwnames=0x0) at ../Include/internal/pycore_call.h:92 #22 method_vectorcall (method=<optimized out>, args=0x7ffff7e8b708 <_PyRuntime+75624>, nargsf=0, kwnames=0x0) at ../Objects/classobject.c:69 #23 0x00007ffff7aa151b in thread_run (boot_raw=0x7fff24007f20) at ../Modules/_threadmodule.c:1114 #24 0x00007ffff791458c in pythread_wrapper (arg=<optimized out>) at ../Python/thread_pthread.h:237 #25 0x00007ffff7698ce1 in start_thread (arg=<optimized out>) at pthread_create.c:447 #26 0x00007ffff771d7d4 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:100

Additional Context

• When using pdb to stop execution before the evaluate_javascript() call, the crash does not occur.
• Adding a delay before calling evaluate_javascript() prevents the crash completely.
• A possible fix would be to track the WebView’s load state and only evaluate JavaScript after the page is loaded.

Environment

• Flatpak 1.16.0
• Python 3.12.9
• Runtime: org.gnome.Platform/x86_64/48
• OS: Arch Linux