Panic after loading a codesandbox page

[CYBAI]

→ ./mach run -Z replace-surrogates https://tsdxi.csb.app/
[2020-06-04T05:30:10Z ERROR script::dom::bindings::conversions] Found an unpaired surrogate in a DOM string. If you see this in real web content, please comment on https://github.com/servo/servo/issues/6564
The above error occurred in the <circle> component:
    in circle (at App.js:8)
    in svg (at App.js:7)
    in div (at App.js:6)
    in App (at src/index.js:9)
    in StrictMode (at src/index.js:8)

Consider adding an error boundary to your tree to customize error handling behavior.
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Error in sandbox:
TypeError: style is undefined
assertion failed: `(left == right)`
  left: `4`,
 right: `1`: This runtime still has live children. (thread ScriptThread PipelineId { namespace_id: PipelineNamespaceId(1), index: PipelineIndex(1) }, at /Users/cybai/.cargo/git/checkouts/rust-mozjs-8611526964119dd6/dbb9bee/src/rust.rs:424)
   0: backtrace::backtrace::libunwind::trace
             at /Users/cybai/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.48/src/backtrace/libunwind.rs:86
      backtrace::backtrace::trace_unsynchronized
             at /Users/cybai/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.48/src/backtrace/mod.rs:66
   1: <servo::backtrace::Print as core::fmt::Debug>::fmt
             at /Volumes/Transcend/codespace/mozilla/servo/ports/winit/backtrace.rs:49
   2: core::fmt::write
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/libcore/fmt/mod.rs:1069
   3: std::io::Write::write_fmt
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/io/mod.rs:1537
   4: servo::backtrace::print
             at /Volumes/Transcend/codespace/mozilla/servo/ports/winit/backtrace.rs:17
   5: servo::main::{{closure}}
             at /Volumes/Transcend/codespace/mozilla/servo/ports/winit/main2.rs:150
   6: std::panicking::rust_panic_with_hook
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/libstd/panicking.rs:481
   7: rust_begin_unwind
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/libstd/panicking.rs:385
   8: std::panicking::begin_panic_fmt
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/libstd/panicking.rs:339
   9: <mozjs::rust::Runtime as core::ops::drop::Drop>::drop
             at /Users/cybai/.cargo/git/checkouts/rust-mozjs-8611526964119dd6/dbb9bee/src/rust.rs:424
  10: core::ptr::drop_in_place
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ptr/mod.rs:178
  11: core::ptr::drop_in_place
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ptr/mod.rs:178
  12: core::ptr::drop_in_place
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ptr/mod.rs:178
  13: <alloc::rc::Rc<T> as core::ops::drop::Drop>::drop
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/liballoc/rc.rs:1150
  14: core::ptr::drop_in_place
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ptr/mod.rs:178
  15: core::ptr::drop_in_place
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ptr/mod.rs:178
  16: <script::script_thread::ScriptThread as script_traits::ScriptThreadFactory>::create::{{closure}}
             at /Volumes/Transcend/codespace/mozilla/servo/components/script/script_thread.rs:806
  17: std::sys_common::backtrace::__rust_begin_short_backtrace
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/sys_common/backtrace.rs:130
  18: std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/thread/mod.rs:475
  19: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/panic.rs:318
  20: std::panicking::try::do_call
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/panicking.rs:297
  21: ___rust_try
  22: std::panicking::try
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/panicking.rs:274
  23: std::panic::catch_unwind
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/panic.rs:394
  24: std::thread::Builder::spawn_unchecked::{{closure}}
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libstd/thread/mod.rs:474
  25: core::ops::function::FnOnce::call_once{{vtable.shim}}
             at /Users/cybai/.rustup/toolchains/nightly-2020-05-15-x86_64-apple-darwin/lib/rustlib/src/rust/src/libcore/ops/function.rs:232
  26: <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/liballoc/boxed.rs:1034
      <alloc::boxed::Box<F> as core::ops::function::FnOnce<A>>::call_once
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/liballoc/boxed.rs:1034
      std::sys::unix::thread::Thread::new::thread_start
             at /rustc/a74d1862d4d87a56244958416fd05976c58ca1a8/src/libstd/sys/unix/thread.rs:87
  27: __pthread_body
  28: __pthread_start
[2020-06-04T05:35:58Z ERROR servo] assertion failed: `(left == right)`
      left: `4`,
     right: `1`: This runtime still has live children.

[garasubo]

This should be reported in #6564?

[CYBAI]

No, it's different from #6564. I do need the surrogate flag to get into the page but this issue is about the panic after loading the page.