diff --git a/extensions/ql-vscode/src/model-editor/flow-model-queries.ts b/extensions/ql-vscode/src/model-editor/flow-model-queries.ts
index 8941774fe..7a38309d2 100644
--- a/extensions/ql-vscode/src/model-editor/flow-model-queries.ts
+++ b/extensions/ql-vscode/src/model-editor/flow-model-queries.ts
@@ -144,9 +144,6 @@ async function runSingleFlowQuery(
 
   // Interpret the results
   const modelsAsDataLanguage = getModelsAsDataLanguage(language);
-  if (!modelsAsDataLanguage) {
-    throw new Error(`No models-as-data definition for ${language}`);
-  }
 
   const definition = modelsAsDataLanguage[type];
 
diff --git a/extensions/ql-vscode/src/model-editor/languages/languages.ts b/extensions/ql-vscode/src/model-editor/languages/languages.ts
index 4d029806b..847e4ae83 100644
--- a/extensions/ql-vscode/src/model-editor/languages/languages.ts
+++ b/extensions/ql-vscode/src/model-editor/languages/languages.ts
@@ -9,6 +9,10 @@ const languages: Partial<Record<QueryLanguage, ModelsAsDataLanguage>> = {
 
 export function getModelsAsDataLanguage(
   language: QueryLanguage,
-): ModelsAsDataLanguage | undefined {
-  return languages[language];
+): ModelsAsDataLanguage {
+  const definition = languages[language];
+  if (!definition) {
+    throw new Error(`No models-as-data definition for ${language}`);
+  }
+  return definition;
 }
diff --git a/extensions/ql-vscode/src/model-editor/yaml.ts b/extensions/ql-vscode/src/model-editor/yaml.ts
index feaf4092a..726b0197d 100644
--- a/extensions/ql-vscode/src/model-editor/yaml.ts
+++ b/extensions/ql-vscode/src/model-editor/yaml.ts
@@ -39,9 +39,6 @@ export function createDataExtensionYaml(
   modeledMethods: readonly ModeledMethod[],
 ) {
   const modelsAsDataLanguage = getModelsAsDataLanguage(language);
-  if (!modelsAsDataLanguage) {
-    throw new Error(`No models as data language for ${language}`);
-  }
 
   const methodsByType: Record<
     Exclude<ModeledMethodType, "none">,
@@ -253,9 +250,6 @@ export function loadDataExtensionYaml(
   }
 
   const modelsAsDataLanguage = getModelsAsDataLanguage(language);
-  if (!modelsAsDataLanguage) {
-    throw new Error(`No models as data language for ${language}`);
-  }
 
   const extensions = data.extensions;
 
diff --git a/extensions/ql-vscode/src/view/model-editor/ModelKindDropdown.tsx b/extensions/ql-vscode/src/view/model-editor/ModelKindDropdown.tsx
index deb989025..0a74327e5 100644
--- a/extensions/ql-vscode/src/view/model-editor/ModelKindDropdown.tsx
+++ b/extensions/ql-vscode/src/view/model-editor/ModelKindDropdown.tsx
@@ -24,9 +24,6 @@ export const ModelKindDropdown = ({
 }: Props) => {
   const predicate = useMemo(() => {
     const modelsAsDataLanguage = getModelsAsDataLanguage(language);
-    if (!modelsAsDataLanguage) {
-      throw new Error(`No models for language ${language}`);
-    }
 
     return modeledMethod?.type && modeledMethod.type !== "none"
       ? modelsAsDataLanguage[modeledMethod.type]