diff --git a/packages/xl-ai/src/streamTool/filterValidOperations.ts b/packages/xl-ai/src/streamTool/filterValidOperations.ts
index 91b513a4f4..c48dab8781 100644
--- a/packages/xl-ai/src/streamTool/filterValidOperations.ts
+++ b/packages/xl-ai/src/streamTool/filterValidOperations.ts
@@ -29,6 +29,7 @@ export async function* filterValidOperations<T>(
   let forceNewOperation = false;
   for await (const chunk of operationsStream) {
     const operation = chunk.operation;
+
     if (operation.ok) {
       yield {
         operation: operation.value,
diff --git a/packages/xl-ai/src/streamTool/preprocess.test.ts b/packages/xl-ai/src/streamTool/preprocess.test.ts
index 814c6455f5..c323aed6c1 100644
--- a/packages/xl-ai/src/streamTool/preprocess.test.ts
+++ b/packages/xl-ai/src/streamTool/preprocess.test.ts
@@ -1,10 +1,7 @@
 import { BlockNoteEditor } from "@blocknote/core";
 import { beforeEach, describe, expect, it } from "vitest";
 import { tools } from "../api/formats/json/tools/index.js";
-import {
-  preprocessOperationsNonStreaming,
-  preprocessOperationsStreaming,
-} from "./preprocess.js";
+import { preprocessOperationsStreaming } from "./preprocess.js";
 import { StreamTool } from "./streamTool.js";
 
 const addOperationValid = {
@@ -148,68 +145,37 @@ describe("preprocess", () => {
     });
   });
 
-  describe("preprocessOperationsNonStreaming", () => {
-    it("should pass valid operations", async () => {
-      async function* mockStream() {
-        yield {
-          partialOperation: addOperationValid,
-          isUpdateToPreviousOperation: false,
-          isPossiblyPartial: false,
-          metadata: undefined,
-        };
-      }
-
-      const results = await collectStreamToArray(
-        preprocessOperationsNonStreaming(mockStream(), streamTools),
-      );
-
-      expect(results.length).toBe(1);
-    });
-
-    it("should throw an error on invalid operations (invalid id)", async () => {
-      async function* mockStream() {
-        yield {
-          partialOperation: addOperationInvalidId,
-          isUpdateToPreviousOperation: false,
-          isPossiblyPartial: false,
-          metadata: undefined,
-        };
-      }
-
-      await expect(
-        collectStreamToArray(
-          preprocessOperationsNonStreaming(mockStream(), streamTools),
-        ),
-      ).rejects.toThrow();
-    });
-
-    it("should throw an error on invalid operations (invalid type)", async () => {
-      async function* mockStream() {
-        yield {
-          partialOperation: invalidOperationType,
-          isUpdateToPreviousOperation: false,
-          isPossiblyPartial: false,
-          metadata: undefined,
-        };
-      }
-
-      await expect(
-        collectStreamToArray(
-          preprocessOperationsNonStreaming(mockStream(), streamTools),
-        ),
-      ).rejects.toThrow();
-    });
-
-    it("should handle empty operation streams", async () => {
-      async function* mockStream() {
-        // Empty stream
-      }
-
-      const results = await collectStreamToArray(
-        preprocessOperationsNonStreaming(mockStream(), streamTools),
-      );
+  it("should throw an error on invalid operations (invalid id)", async () => {
+    async function* mockStream() {
+      yield {
+        partialOperation: addOperationInvalidId,
+        isUpdateToPreviousOperation: false,
+        isPossiblyPartial: false,
+        metadata: undefined,
+      };
+    }
+
+    await expect(
+      collectStreamToArray(
+        preprocessOperationsStreaming(mockStream(), streamTools),
+      ),
+    ).rejects.toThrow();
+  });
 
-      expect(results).toHaveLength(0);
-    });
+  it("should throw an error on invalid operations (invalid type)", async () => {
+    async function* mockStream() {
+      yield {
+        partialOperation: invalidOperationType,
+        isUpdateToPreviousOperation: false,
+        isPossiblyPartial: false,
+        metadata: undefined,
+      };
+    }
+
+    await expect(
+      collectStreamToArray(
+        preprocessOperationsStreaming(mockStream(), streamTools),
+      ),
+    ).rejects.toThrow();
   });
 });
diff --git a/packages/xl-ai/src/streamTool/preprocess.ts b/packages/xl-ai/src/streamTool/preprocess.ts
index a395059c15..7af54daf11 100644
--- a/packages/xl-ai/src/streamTool/preprocess.ts
+++ b/packages/xl-ai/src/streamTool/preprocess.ts
@@ -1,3 +1,4 @@
+import { getErrorMessage } from "@ai-sdk/provider-utils";
 import { ChunkExecutionError } from "./ChunkExecutionError.js";
 import { filterValidOperations } from "./filterValidOperations.js";
 import { StreamTool, StreamToolCall } from "./streamTool.js";
@@ -36,47 +37,16 @@ export async function* preprocessOperationsStreaming<
     (chunk) => {
       if (!chunk.isPossiblyPartial) {
         // only throw if the operation is not possibly partial
-        
-        throw new ChunkExecutionError("invalid operation: " + chunk.operation.error, chunk);
+        throw new ChunkExecutionError(
+          `Invalid operation. ${getErrorMessage(chunk.operation.error)}`,
+          chunk,
+          {
+            cause: chunk.operation.error,
+          },
+        );
       }
     },
   );
 
   yield* validOperationsStream;
 }
-
-/**
- * Validates an stream of operations and throws an error if an invalid operation is found.
- *
- * TODO: remove
- *
- * @deprecated
- */
-export async function* preprocessOperationsNonStreaming<
-  T extends StreamTool<any>[],
->(
-  operationsStream: AsyncIterable<{
-    partialOperation: any;
-    isUpdateToPreviousOperation: boolean;
-    isPossiblyPartial: boolean;
-    metadata: any;
-  }>,
-  streamTools: T,
-): AsyncGenerator<PreprocessOperationResult<T>> {
-  // from partial operations to valid / invalid operations
-  const validatedOperationsStream = toValidatedOperations(
-    operationsStream,
-    streamTools,
-  );
-
-  // filter valid operations, invalid operations should throw an error
-  const validOperationsStream = filterValidOperations(
-    validatedOperationsStream,
-    (chunk) => {
-      throw new Error("invalid operation: " + chunk.operation.error);
-    },
-  );
-
-  // yield results
-  yield* validOperationsStream;
-}
diff --git a/packages/xl-ai/src/streamTool/toValidatedOperations.ts b/packages/xl-ai/src/streamTool/toValidatedOperations.ts
index f1dd5af047..97dc65fade 100644
--- a/packages/xl-ai/src/streamTool/toValidatedOperations.ts
+++ b/packages/xl-ai/src/streamTool/toValidatedOperations.ts
@@ -22,6 +22,18 @@ export async function* toValidatedOperations<T extends StreamTool<any>[]>(
   metadata: any;
 }> {
   for await (const chunk of partialObjectStream) {
+    if (!chunk.partialOperation.type) {
+      yield {
+        operation: {
+          ok: false,
+          error: "The `type` property of an operation is required.",
+        },
+        isUpdateToPreviousOperation: chunk.isUpdateToPreviousOperation,
+        isPossiblyPartial: chunk.isPossiblyPartial,
+        metadata: chunk.metadata,
+      };
+      continue;
+    }
     const func = streamTools.find(
       (f) => f.name === chunk.partialOperation.type,
     )!;
diff --git a/packages/xl-ai/src/streamTool/vercelAiSdk/util/chatHandlers.ts b/packages/xl-ai/src/streamTool/vercelAiSdk/util/chatHandlers.ts
index 5bab921d7f..2014b2d8a8 100644
--- a/packages/xl-ai/src/streamTool/vercelAiSdk/util/chatHandlers.ts
+++ b/packages/xl-ai/src/streamTool/vercelAiSdk/util/chatHandlers.ts
@@ -129,6 +129,8 @@ export async function setupToolCallStreaming(
 
   if (result.status === "rejected") {
     if (result.reason instanceof ChunkExecutionError) {
+      // all errors thrown in the pipeline should be ChunkExecutionErrors,
+      // so we can retrieve the chunk that caused the error
       error = result.reason;
     } else {
       if (!chat.error) {