fix: prevent jsonPath method from being serialized in schema output

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@tinybirdco/sdk",
-  "version": "0.0.58",
+  "version": "0.0.59",
   "description": "TypeScript SDK for Tinybird Forward - define datasources and pipes as TypeScript",
   "type": "module",
   "main": "./dist/index.js",

src/schema/datasource.test.ts

@@ -7,7 +7,7 @@ import {
   getColumnNames,
   column,
 } from "./datasource.js";
-import { t } from "./types.js";
+import { t, type AnyTypeValidator } from "./types.js";
 import { engine } from "./engines.js";
 import { defineKafkaConnection, defineS3Connection, defineGCSConnection } from "./connection.js";
 
@@ -259,6 +259,20 @@ describe("Datasource Schema", () => {
       expect(result).toBeUndefined();
     });
 
+    it("never returns a function when validator branding is missing", () => {
+      const validator = t.string();
+      // Simulate a validator-like object where isTypeValidator() fails by
+      // removing symbol keys (including the validator brand).
+      const unbrandedValidator = Object.fromEntries(
+        Object.entries(validator as unknown as Record<string, unknown>)
+      ) as unknown as AnyTypeValidator;
+
+      const result = getColumnJsonPath(unbrandedValidator);
+
+      expect(result).toBeUndefined();
+      expect(typeof result).not.toBe("function");
+    });
+
     it("returns jsonPath from validator modifier", () => {
       const validator = t.string().jsonPath("$.user.id");
       const result = getColumnJsonPath(validator);

src/schema/datasource.ts

@@ -272,7 +272,9 @@ export function getColumnJsonPath(column: AnyTypeValidator | ColumnDefinition):
     return getModifiers(column).jsonPath;
   }
 
-  if (column.jsonPath !== undefined) {
+  // Check typeof to avoid returning the jsonPath method from validators
+  // if isTypeValidator incorrectly returns false (e.g., cross-module Symbol issues)
+  if (typeof column.jsonPath === "string") {
     return column.jsonPath;
   }