diff --git a/packages/algoliasearch/src/__tests__/default.test.ts b/packages/algoliasearch/src/__tests__/default.test.ts
index 40b29a658..f7a6ec534 100644
--- a/packages/algoliasearch/src/__tests__/default.test.ts
+++ b/packages/algoliasearch/src/__tests__/default.test.ts
@@ -191,22 +191,22 @@ describe('default preset', () => {
       expect(() =>
         // @ts-ignore
         algoliasearch('APP_ID', 'API_KEY', { transformation: { region: 'cn' } })
-      ).toThrow('`region` is required and must be one of the following: eu, us}`');
+      ).toThrow('`region` is required and must be one of the following: eu, us');
     });
 
-    test('throws when calling the transformation methods without init parameters', async () => {
-      await expect(
+    test('throws when calling the transformation methods without init parameters', () => {
+      expect(() =>
         index.saveObjectsWithTransformation([{ objectID: 'bar', baz: 42 }], { waitForTasks: true })
-      ).rejects.toThrow(
-        '`transformation.region` must be provided at client instantiation before calling this method.'
+      ).toThrow(
+        '`options.transformation.region` must be provided at client instantiation before calling this method.'
       );
 
-      await expect(
+      expect(() =>
         index.partialUpdateObjectsWithTransformation([{ objectID: 'bar', baz: 42 }], {
           waitForTasks: true,
         })
-      ).rejects.toThrow(
-        '`transformation.region` must be provided at client instantiation before calling this method.'
+      ).toThrow(
+        '`options.transformation.region` must be provided at client instantiation before calling this method.'
       );
     });
 
diff --git a/packages/algoliasearch/src/builds/browser.ts b/packages/algoliasearch/src/builds/browser.ts
index 45270ac66..c8fd01534 100644
--- a/packages/algoliasearch/src/builds/browser.ts
+++ b/packages/algoliasearch/src/builds/browser.ts
@@ -207,6 +207,7 @@ import {
   createIngestionClient,
   partialUpdateObjectsWithTransformation,
   saveObjectsWithTransformation,
+  transformationConfigurationError,
 } from '../ingestion';
 import {
   AlgoliaSearchOptions,
@@ -261,7 +262,9 @@ export default function algoliasearch(
 
   if (options && options.transformation) {
     if (!options.transformation.region) {
-      throw new Error('`region` must be provided when leveraging the transformation pipeline');
+      throw transformationConfigurationError(
+        '`region` must be provided when leveraging the transformation pipeline'
+      );
     }
 
     ingestionTransporter = createIngestionClient({ ...options, ...commonOptions });
diff --git a/packages/algoliasearch/src/builds/node.ts b/packages/algoliasearch/src/builds/node.ts
index c24525b8d..db263600b 100644
--- a/packages/algoliasearch/src/builds/node.ts
+++ b/packages/algoliasearch/src/builds/node.ts
@@ -209,6 +209,7 @@ import {
   createIngestionClient,
   partialUpdateObjectsWithTransformation,
   saveObjectsWithTransformation,
+  transformationConfigurationError,
 } from '../ingestion';
 import {
   AlgoliaSearchOptions,
@@ -261,7 +262,9 @@ export default function algoliasearch(
 
   if (options && options.transformation) {
     if (!options.transformation.region) {
-      throw new Error('`region` must be provided when leveraging the transformation pipeline');
+      throw transformationConfigurationError(
+        '`region` must be provided when leveraging the transformation pipeline'
+      );
     }
 
     ingestionTransporter = createIngestionClient({ ...options, ...commonOptions });
diff --git a/packages/algoliasearch/src/ingestion.ts b/packages/algoliasearch/src/ingestion.ts
index abeb5c311..c3bd940b9 100644
--- a/packages/algoliasearch/src/ingestion.ts
+++ b/packages/algoliasearch/src/ingestion.ts
@@ -21,11 +21,15 @@ export function createIngestionClient(
   options: SearchClientOptions & ClientTransporterOptions & TransformationOptions
 ): IngestionClient {
   if (!options || !options.transformation || !options.transformation.region) {
-    throw new Error('`region` must be provided when leveraging the transformation pipeline');
+    throw transformationConfigurationError(
+      '`region` must be provided when leveraging the transformation pipeline'
+    );
   }
 
   if (options.transformation.region !== 'eu' && options.transformation.region !== 'us') {
-    throw new Error('`region` is required and must be one of the following: eu, us');
+    throw transformationConfigurationError(
+      '`region` is required and must be one of the following: eu, us'
+    );
   }
 
   const appId = options.appId;
@@ -66,29 +70,37 @@ export function createIngestionClient(
         transporter.responsesCache.clear(),
       ]).then(() => undefined);
     },
-    async push(
+    push(
       { indexName, pushTaskPayload, watch }: PushProps,
       requestOptions?: RequestOptions
-    ): Promise<WatchResponse> {
+    ): Readonly<Promise<WatchResponse>> {
       if (!indexName) {
-        throw new Error('Parameter `indexName` is required when calling `push`.');
+        throw transformationConfigurationError(
+          'Parameter `indexName` is required when calling `push`.'
+        );
       }
 
       if (!pushTaskPayload) {
-        throw new Error('Parameter `pushTaskPayload` is required when calling `push`.');
+        throw transformationConfigurationError(
+          'Parameter `pushTaskPayload` is required when calling `push`.'
+        );
       }
 
       if (!pushTaskPayload.action) {
-        throw new Error('Parameter `pushTaskPayload.action` is required when calling `push`.');
+        throw transformationConfigurationError(
+          'Parameter `pushTaskPayload.action` is required when calling `push`.'
+        );
       }
 
       if (!pushTaskPayload.records) {
-        throw new Error('Parameter `pushTaskPayload.records` is required when calling `push`.');
+        throw transformationConfigurationError(
+          'Parameter `pushTaskPayload.records` is required when calling `push`.'
+        );
       }
 
       const opts: RequestOptions = requestOptions || { queryParameters: {} };
 
-      return await transporter.write<WatchResponse>(
+      return transporter.write<WatchResponse>(
         {
           method: MethodEnum.Post,
           path: encode('1/push/%s', indexName),
@@ -107,12 +119,12 @@ export function createIngestionClient(
 }
 
 export function saveObjectsWithTransformation(indexName: string, client?: IngestionClient) {
-  return async (
+  return (
     objects: ReadonlyArray<Readonly<Record<string, any>>>,
     requestOptions?: RequestOptions & ChunkOptions & SaveObjectsOptions & PushOptions
-  ): Promise<WatchResponse> => {
+  ): Readonly<Promise<WatchResponse>> => {
     if (!client) {
-      throw new Error(
+      throw transformationConfigurationError(
         '`options.transformation.region` must be provided at client instantiation before calling this method.'
       );
     }
@@ -124,7 +136,7 @@ export function saveObjectsWithTransformation(indexName: string, client?: Ingest
       : BatchActionEnum.UpdateObject;
 
     /* eslint functional/immutable-data: "off" */
-    return await client.push(
+    return client.push(
       {
         indexName,
         pushTaskPayload: { action, records: objects },
@@ -139,12 +151,12 @@ export function partialUpdateObjectsWithTransformation(
   indexName: string,
   client?: IngestionClient
 ) {
-  return async (
+  return (
     objects: ReadonlyArray<Readonly<Record<string, any>>>,
     requestOptions?: RequestOptions & ChunkOptions & PartialUpdateObjectsOptions & PushOptions
-  ): Promise<WatchResponse> => {
+  ): Readonly<Promise<WatchResponse>> => {
     if (!client) {
-      throw new Error(
+      throw transformationConfigurationError(
         '`options.transformation.region` must be provided at client instantiation before calling this method.'
       );
     }
@@ -156,7 +168,7 @@ export function partialUpdateObjectsWithTransformation(
       : BatchActionEnum.PartialUpdateObjectNoCreate;
 
     /* eslint functional/immutable-data: "off" */
-    return await client.push(
+    return client.push(
       {
         indexName,
         pushTaskPayload: { action, records: objects },
@@ -166,3 +178,10 @@ export function partialUpdateObjectsWithTransformation(
     );
   };
 }
+
+export function transformationConfigurationError(message: string): Error {
+  return {
+    name: 'TransformationConfigurationError',
+    message,
+  };
+}
diff --git a/packages/algoliasearch/src/types/Ingestion.ts b/packages/algoliasearch/src/types/Ingestion.ts
index 04ad3b99d..b483a1567 100644
--- a/packages/algoliasearch/src/types/Ingestion.ts
+++ b/packages/algoliasearch/src/types/Ingestion.ts
@@ -25,7 +25,7 @@ export type IngestionMethods = {
   readonly saveObjectsWithTransformation: (
     objects: ReadonlyArray<Readonly<Record<string, any>>>,
     requestOptions?: RequestOptions & ChunkOptions & SaveObjectsOptions & PushOptions
-  ) => Promise<WatchResponse>;
+  ) => Readonly<Promise<WatchResponse>>;
 
   /**
    * Helper: Similar to the `partialUpdateObjects` method but requires a Push connector (https://www.algolia.com/doc/guides/sending-and-managing-data/send-and-update-your-data/connectors/push/) to be created first, in order to transform records before indexing them to Algolia. The `region` must've been passed to the client instantiation method.
@@ -36,7 +36,7 @@ export type IngestionMethods = {
   readonly partialUpdateObjectsWithTransformation: (
     objects: ReadonlyArray<Readonly<Record<string, any>>>,
     requestOptions?: RequestOptions & ChunkOptions & PartialUpdateObjectsOptions & PushOptions
-  ) => Promise<WatchResponse>;
+  ) => Readonly<Promise<WatchResponse>>;
 };
 
 export type WatchResponse = {
@@ -108,5 +108,5 @@ export type IngestionClient = BaseSearchClient & {
   readonly push: (
     { indexName, pushTaskPayload, watch }: PushProps,
     requestOptions?: RequestOptions
-  ) => Promise<WatchResponse>;
+  ) => Readonly<Promise<WatchResponse>>;
 };