Turbopack Error: FileSystemPath("").join("../$root_dir/webapp") leaves the filesystem root

[louishectorcode]

Running bun dev with the flag next dev --turbopack generates the following error.

Turbopack version: v15.4.0-canary.129-16-g27a271bd6
Next.js version: 15.4.1

Error message:

Turbopack Error: FileSystemPath("").join("../$root_dir/webapp") leaves the filesystem root

Debug info:
- Execution of get_entrypoints_with_issues_operation failed
- Execution of EntrypointsOperation::new failed
- Execution of Project::entrypoints failed
- Execution of Project::middleware_endpoint failed
- Execution of *MiddlewareEndpoint::new failed
- Execution of Project::middleware_context failed
- Execution of *parse_config_from_source failed
- Execution of *ProcessResult::module failed
- Execution of *AssetContext::process failed
- Execution of Project::edge_middleware_context failed
- Execution of AppProject::edge_ecmascript_client_reference_transition failed
- Execution of *NextEcmascriptClientReferenceTransition::new failed
- Execution of AppProject::client_transition failed
- Execution of *FullContextTransition::new failed
- Execution of AppProject::client_module_context failed
- Execution of *ModuleAssetContext::new failed
- Execution of AppProject::client_module_options_context failed
- Execution of *get_client_module_options_context failed
- Execution of Project::execution_context failed
- Execution of Project::node_root failed
- FileSystemPath("").join("../$root_dir/webapp") leaves the filesystem root]

[apostolos]

#81628 (comment)