chore: better error message for exhaustive

Author: peter-sanderson

packages/type-utils/src/exhaustive.ts

@@ -0,0 +1,9 @@
+class UnreachableCaseError extends Error {
+    constructor(val: never, message: string) {
+        super(`${message}: [${JSON.stringify(val)}]`);
+    }
+}
+
+export const exhaustive = (unhandledCase: never, message = 'Unreachable case'): never => {
+    throw new UnreachableCaseError(unhandledCase, message);
+};

packages/type-utils/src/index.ts

@@ -3,3 +3,4 @@ export * from './overloads';
 export * from './timeout';
 export * from './utils';
 export * from './object';
+export * from './exhaustive';

packages/type-utils/src/utils.ts

@@ -132,7 +132,3 @@ export type FilterOutFromUnionByTypeProperty<
         ? never
         : { [K in KeyName]: Exclude<ActualValue, ValueToExclude> } & Omit<Union, KeyName>
     : Union;
-
-export const exhaustive = (unhandledCase: never): never => {
-    throw new Error(`Unhandled case ${unhandledCase}`);
-};