swc-project/swc · error

Module {} is not registered

Error message

Module {} is not registered

What it means

Raised via unreachable!() in get_for_merging (bundler merge.rs:72). Before merging a chunk, the bundler looks up the module by ModuleId in its scope; the invariant is that every module scheduled for merging was already registered during load/analyze. If scope.get_module(id) returns None, the chunk's module list references a module the bundler never stored, and this panic reports that broken invariant, naming the unregistered ModuleId.

Source

Thrown at crates/swc_bundler/src/bundler/chunk/merge.rs:72

    }
}

impl<L, R> Bundler<'_, L, R>
where
    L: Load,
    R: Resolve,
{
    pub(super) fn get_for_merging(
        &self,
        ctx: &Ctx,
        id: ModuleId,
        is_entry: bool,
    ) -> Result<Modules, Error> {
        self.run(|| {
            let info = self
                .scope
                .get_module(id)
                .unwrap_or_else(|| unreachable!("Module {} is not registered", id));
            let mut module = self.apply_hooks(id, is_entry)?;
            module = self.prepare_for_merging(ctx, &info, module)?;

            if !is_entry {
                module = self.wrap_cjs_module(ctx, &info, module)?;
            }
            self.replace_cjs_require_calls(&info, &mut module, is_entry);

            Ok(module)
        })
    }

    /// This method sort modules.
    pub(super) fn merge_into_entry(
        &self,
        ctx: &Ctx,
        entry_id: ModuleId,
        entry: &mut Modules,

View on GitHub (pinned to 5176682b65)

Solutions

1. Check for and surface load/analyze errors that prevented the module from being registered before chunking
2. Ensure all dependency modules are resolved and registered before modules are assigned to chunks
3. Convert the unreachable! into a proper bundler Error including the ModuleId so callers can report it

When it happens

Trigger: Thrown at crates/swc_bundler/src/bundler/chunk/merge.rs:72 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of swc-project/swc@5176682b65 (2026-08-17). Data as JSON: /api/errors/511b7f882375b8da. Report an issue: GitHub.