[BUG] swc_bundler example panick for multiple default exports (unreachable code is reached)

[Charlie-XIAO]

I used the example bundler code, where the contents of assets/main.js are:

export default a = 1;
export default b = 1;

Here is the repo containing the full minimal reproducible example, if the above is not clear enough: https://github.com/CSCI-SHU-410-SE-Project/repr-swc-multi-default-export.

However this causes an internal panic that I cannot recover from (entered unreachable code):

thread 'main' panicked at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\inline.rs:49:13:
internal error: entered unreachable code: Multiple identifiers equivalent up to span hygiene found: default#6
First = default#5
Second = default#5

Stack backtrace

   0: std::panicking::begin_panic_handler
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library\std\src\panicking.rs:645
   1: core::panicking::panic_fmt
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce/library\core\src\panicking.rs:72
   2: swc_bundler::inline::Analyzer::store
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\inline.rs:49
   3: swc_bundler::inline::impl$1::visit_var_declarator
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\inline.rs:81
   4: swc_ecma_visit::visit_var_declarators::closure$0<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
   5: core::slice::iter::impl$181::for_each<swc_ecma_ast::decl::VarDeclarator,swc_ecma_visit::visit_var_declarators::closure_env$0<swc_bundler::inline::Analyzer> >
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\slice\iter\macros.rs:254
   6: swc_ecma_visit::visit_var_declarators<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
   7: swc_ecma_visit::Visit::visit_var_declarators<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
   8: swc_ecma_visit::visit_var_decl<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
   9: swc_ecma_visit::impl$629::visit_children_with<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  10: swc_bundler::inline::impl$1::visit_var_decl
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\inline.rs:75
  11: swc_ecma_visit::visit_decl<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  12: swc_ecma_visit::Visit::visit_decl<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  13: swc_ecma_visit::visit_stmt<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  14: swc_ecma_visit::Visit::visit_stmt<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  15: swc_ecma_visit::visit_module_item<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  16: swc_ecma_visit::Visit::visit_module_item<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  17: swc_ecma_visit::impl$444::visit_with<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_ecma_visit-0.98.7\src\lib.rs:540
  18: swc_bundler::modules::impl$0::visit_with::closure$0<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\modules\mod.rs:229
  19: core::iter::traits::iterator::Iterator::for_each::call::closure$0<tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::ModuleItem> > >,swc_bundler::modules::impl$0::visit_with::closure_env$0<swc_bundler::inline::Analyzer> >
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\traits\iterator.rs:855
  20: core::ops::function::impls::impl$3::call_mut<tuple$<tuple$<>,tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::ModuleItem> > > >,core::iter::traits::iterator::Iterator::for_each::call::closure_env$0<tuple$<swc_bundler::id::ModuleId,ref$<e
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\ops\function.rs:294
  21: core::ops::function::impls::impl$3::call_mut<tuple$<tuple$<>,tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::ModuleItem> > > >,ref_mut$<core::iter::traits::iterator::Iterator::for_each::call::closure_env$0<tuple$<swc_bundler::id::Module
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\ops\function.rs:294
  22: core::iter::adapters::map::map_fold::closure$0<ref$<enum2$<swc_ecma_ast::module::ModuleItem> >,tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::ModuleItem> > >,tuple$<>,swc_bundler::modules::impl$0::iter::closure$1::closure_env$0,ref_mut
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:85
  23: core::slice::iter::impl$181::fold<enum2$<swc_ecma_ast::module::ModuleItem>,tuple$<>,core::iter::adapters::map::map_fold::closure_env$0<ref$<enum2$<swc_ecma_ast::module::ModuleItem> >,tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::Modul
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\slice\iter\macros.rs:232
  24: core::iter::adapters::map::impl$2::fold<tuple$<swc_bundler::id::ModuleId,ref$<enum2$<swc_ecma_ast::module::ModuleItem> > >,core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::impl$0::iter::closure$1::closure_env$0,tupl
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:125
  25: core::iter::adapters::flatten::impl$35::fold::flatten::closure$0<core::iter::adapters::map::Map<core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::impl$0::iter::closure$1::closure_env$0>,tuple$<>,ref_mut$<core::iter::
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\flatten.rs:656
  26: core::iter::adapters::flatten::impl$33::iter_fold::flatten::closure$0<core::iter::adapters::map::Map<core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::impl$0::iter::closure$1::closure_env$0>,tuple$<>,core::iter::adap
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\flatten.rs:467
  27: core::iter::adapters::map::map_fold::closure$0<ref$<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,core::iter::adapters::map::Map<core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::impl$0::iter::clos
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:85
  28: core::slice::iter::impl$181::fold<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module>,tuple$<>,core::iter::adapters::map::map_fold::closure_env$0<ref$<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,core::iter::adapters::map::M
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\slice\iter\macros.rs:232
  29: core::iter::adapters::map::impl$2::fold<core::iter::adapters::map::Map<core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::impl$0::iter::closure$1::closure_env$0>,core::slice::iter::Iter<tuple$<swc_bundler::id::ModuleI
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:125
  30: core::iter::adapters::fuse::impl$3::fold<core::iter::adapters::map::Map<core::slice::iter::Iter<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,swc_bundler::modules::impl$0::iter::closure_env$1>,tuple$<>,core::iter::adapters::flatten::imp
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\fuse.rs:94
  31: core::iter::adapters::flatten::FlattenCompat<core::iter::adapters::map::Map<core::slice::iter::Iter<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,swc_bundler::modules::impl$0::iter::closure_env$1>,core::iter::adapters::map::Map<core::sl
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\flatten.rs:474
  32: core::iter::adapters::flatten::impl$35::fold<core::iter::adapters::map::Map<core::slice::iter::Iter<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,swc_bundler::modules::impl$0::iter::closure_env$1>,core::iter::adapters::map::Map<core::sl
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\flatten.rs:659
  33: core::iter::adapters::flatten::impl$3::fold<core::slice::iter::Iter<tuple$<swc_bundler::id::ModuleId,swc_ecma_ast::module::Module> >,core::iter::adapters::map::Map<core::slice::iter::Iter<enum2$<swc_ecma_ast::module::ModuleItem> >,swc_bundler::modules::im
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\flatten.rs:81
  34: core::iter::adapters::chain::impl$1::fold<core::iter::adapters::flatten::FlatMap<std::collections::hash::map::Iter<swc_bundler::id::ModuleId,alloc::vec::Vec<enum2$<swc_ecma_ast::module::ModuleItem>,alloc::alloc::Global> >,core::iter::adapters::map::Map<co
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\chain.rs:93
  35: core::iter::adapters::chain::impl$1::fold<core::iter::adapters::chain::Chain<core::iter::adapters::flatten::FlatMap<std::collections::hash::map::Iter<swc_bundler::id::ModuleId,alloc::vec::Vec<enum2$<swc_ecma_ast::module::ModuleItem>,alloc::alloc::Global>
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\chain.rs:90
  36: core::iter::traits::iterator::Iterator::for_each<core::iter::adapters::chain::Chain<core::iter::adapters::chain::Chain<core::iter::adapters::flatten::FlatMap<std::collections::hash::map::Iter<swc_bundler::id::ModuleId,alloc::vec::Vec<enum2$<swc_ecma_ast::
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\traits\iterator.rs:858
  37: swc_bundler::modules::Modules::visit_with<swc_bundler::inline::Analyzer>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\modules\mod.rs:229
  38: swc_bundler::inline::inline
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\inline.rs:27
  39: swc_bundler::bundler::Bundler<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>::finalize_merging_of_entry<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\chunk\merge.rs:434
  40: swc_bundler::bundler::chunk::merge::impl$1::merge_into_entry::closure$0<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\chunk\merge.rs:129
  41: scoped_tls::ScopedKey<swc_common::syntax_pos::Globals>::set<swc_common::syntax_pos::Globals,swc_bundler::bundler::chunk::merge::impl$1::merge_into_entry::closure_env$0<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>,tuple$<> >
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\scoped-tls-1.0.1\src\lib.rs:137
  42: better_scoped_tls::ScopedKey<swc_common::syntax_pos::Globals>::set<swc_common::syntax_pos::Globals,swc_bundler::bundler::chunk::merge::impl$1::merge_into_entry::closure_env$0<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>,tup
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\better_scoped_tls-0.1.1\src\lib.rs:55
  43: swc_bundler::bundler::Bundler<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>::run<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver,swc_bundler::bundler::chunk::merge::impl$1::merge_into_entry::closu
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\mod.rs:218
  44: swc_bundler::bundler::Bundler<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>::merge_into_entry<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\chunk\merge.rs:97
  45: swc_bundler::bundler::chunk::impl$0::chunk::closure$2<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\chunk\mod.rs:103
  46: core::iter::adapters::map::map_try_fold::closure$0<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::vec::in_place_drop::InPlaceDrop<swc_bundler::bundler::Bundle>,enum2$<
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:92
  47: core::iter::traits::iterator::Iterator::try_fold<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global>,alloc::vec::in_place_drop::InPlaceDrop<swc_bundler::bundler::Bundle>,core::iter::adapter
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\traits\iterator.rs:2462
  48: core::iter::adapters::map::impl$2::try_fold<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global>,swc_bundler::bundler::chunk::
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:118
  49: core::iter::adapters::map::impl$2::try_fold<swc_bundler::bundler::Bundle,core::iter::adapters::map::Map<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global>,swc_bundler::bundler::chunk::impl
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\adapters\map.rs:118
  50: alloc::vec::in_place_collect::impl$2::collect_in_place<swc_bundler::bundler::Bundle,core::iter::adapters::map::Map<core::iter::adapters::map::Map<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc:
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\alloc\src\vec\in_place_collect.rs:366
  51: alloc::vec::in_place_collect::impl$1::from_iter<swc_bundler::bundler::Bundle,core::iter::adapters::map::Map<core::iter::adapters::map::Map<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\alloc\src\vec\in_place_collect.rs:253
  52: alloc::vec::impl$14::from_iter<swc_bundler::bundler::Bundle,core::iter::adapters::map::Map<core::iter::adapters::map::Map<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global>,swc_bundler::bu
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\alloc\src\vec\mod.rs:2791
  53: core::iter::traits::iterator::Iterator::collect<core::iter::adapters::map::Map<core::iter::adapters::map::Map<alloc::vec::into_iter::IntoIter<tuple$<swc_bundler::id::ModuleId,swc_bundler::modules::Modules>,alloc::alloc::Global>,swc_bundler::bundler::chunk
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\iter\traits\iterator.rs:2054
  54: swc_bundler::bundler::Bundler<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>::chunk<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\chunk\mod.rs:100
  55: swc_bundler::bundler::Bundler<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>::bundle<swc_multi_default_export::PathLoader,swc_multi_default_export::PathResolver>
             at C:\Users\lenovo\.cargo\registry\src\index.crates.io-6f17d22bba15001f\swc_bundler-0.225.18\src\bundler\mod.rs:199
  56: swc_multi_default_export::main
             at .\src\main.rs:31
  57: core::ops::function::FnOnce::call_once<void (*)(),tuple$<> >
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\ops\function.rs:250
  58: core::hint::black_box
             at /rustc/07dca489ac2d933c78d3c5158e3f43beefeb02ce\library\core\src\hint.rs:286
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
error: process didn't exit successfully: `target\debug\swc-multi-default-export.exe` (exit code: 101)

I understand that the bundler code is not actively maintained, but given this is not a recoverable error, would you please consider a fix? Thanks.