{"record":{"id":"f1ed41397923cc09","repo":"BoundaryML/baml","slug":"attempted-to-read-a-property-that-has-no-defined-type-this-f1ed41","errorCode":null,"errorMessage":"attempted to read a property that has no defined type, this is likely an internal bug","messagePattern":"attempted to read a property that has no defined type, this is likely an internal bug","errorType":"exception","errorClass":"napi::Error","httpStatus":null,"severity":"error","filePath":"engine/language_client_typescript/src/types/type_builder.rs","lineNumber":310,"sourceCode":"#[napi]\nimpl ClassPropertyBuilder {\n    #[napi]\n    pub fn set_type(&self, field_type: &FieldType) -> Self {\n        self.inner\n            .lock()\n            .unwrap()\n            .set_type(field_type.inner.lock().unwrap().clone());\n        self.inner.clone().into()\n    }\n\n    #[napi]\n    pub fn get_type(&self) -> napi::Result<FieldType> {\n        self.inner\n            .lock()\n            .unwrap()\n            .r#type()\n            .map(FieldType::from)\n            .ok_or_else(|| crate::errors::from_anyhow_error(anyhow::anyhow!(\n                \"attempted to read a property that has no defined type, this is likely an internal bug\"\n            )))\n    }\n\n    #[napi]\n    pub fn alias(&self, alias: Option<String>) -> Self {\n        self.inner.lock().unwrap().with_meta(\n            \"alias\",\n            alias.map_or(baml_types::BamlValue::Null, BamlValue::String),\n        );\n        self.inner.clone().into()\n    }\n\n    #[napi]\n    pub fn description(&self, description: Option<String>) -> Self {\n        self.inner.lock().unwrap().with_meta(\n            \"description\",\n            description.map_or(baml_types::BamlValue::Null, BamlValue::String),","sourceCodeStart":292,"sourceCodeEnd":328,"githubUrl":"https://github.com/BoundaryML/baml/blob/bd85ce9dee1463ff04d27efd20531013a4ff46c1/engine/language_client_typescript/src/types/type_builder.rs#L292-L328","documentation":"ClassPropertyViewer.getType() could not obtain a defined type for the property from the underlying runtime type builder; r#type() returned None. The library treats a property without a type as an internal inconsistency, so it raises an anyhow-derived error labelled an internal bug.","triggerScenarios":"Inspecting a property created without calling setType()/setType first (via ClassBuilder.addProperty with an unset type path); viewing a property whose type was removed or never initialized in the type builder; races where the underlying type-builder object was reset before viewing.","commonSituations":"Iterating listProperties() on a freshly added class property that has no type yet; dynamically constructed type builders where a property was declared but never given a type; N-API handle lifecycle issues after runtime teardown.","solutions":["Always set the property type (bldr.property(name).setType(...)) before reading it via property()/getType()","Check that you are viewing the property after addProperty completed with a type argument","If iterating properties, skip or default-handle properties whose type is not yet set","Report to BAML if the property was definitely given a type — it indicates a binding bug"],"exampleFix":"// before\nconst p = clsBuilder.addProperty(\"name\"); // type set later, too late\n// after\nconst p = clsBuilder.addProperty(\"name\", \"string\");","handlingStrategy":"validation","validationCode":"if (!clsBuilder.listProperties().some(([n]) => n === propName)) throw new Error('unknown property');","typeGuard":"null","tryCatchPattern":"try { const t = prop.getType(); } catch (e) {\n  if (e.message.includes('no defined type')) { /* property has no type yet */ }\n  else throw e;\n}","preventionTips":["Always pass a type to addProperty","Only view properties after their type is set","Treat this error as a bug report trigger if types were definitely set"],"tags":["rust","napi","type-builder","internal-bug","property"],"backgroundTag":"internal-invariant-violation","analyzedSha":"bd85ce9dee1463ff04d27efd20531013a4ff46c1","analyzedAt":"2026-09-12T03:38:25.718Z","contentChangedAt":"2026-09-12T03:38:25.718Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}