diff --git a/ui/src/Services/API.ts b/ui/src/Services/API.ts
index 9a6e4f93..0b784b7f 100644
--- a/ui/src/Services/API.ts
+++ b/ui/src/Services/API.ts
@@ -39,8 +39,8 @@ interface APIErrorResponse {
   data: unknown;
 }
 
-export interface APIError {
-  message?: string;
+export interface APIError extends Error {
+  message: string;
   code?: string;
   response?: APIErrorResponse;
 }
diff --git a/ui/src/types.ts b/ui/src/types.ts
index 64eee51f..5e14ec4e 100644
--- a/ui/src/types.ts
+++ b/ui/src/types.ts
@@ -194,7 +194,7 @@ export interface InstanceLabel {
   types: SimpleType[];
   id: UUID;
   name: string;
-  error: Error;
+  error?: Error;
 }
 
 export type Fields = Record<string,StructureOfField>; // by fieldName