include version number in StagehandDefaultError (#807)

# why
- for a better debugging experience
# what changed
- added build step `gen-version.ts` which will read the `package.json`
and expose the stagehand version number as a const globally
- included the version in the `StagehandDefaultError` message
# test plan
- regressions

Author: seanmcguire12

.changeset/gentle-turtles-stay.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+include version number in StagehandDefaultError message

package.json

@@ -20,7 +20,8 @@
     "build-dom-scripts": "tsx lib/dom/genDomScripts.ts",
     "build-types": "tsc --emitDeclarationOnly --outDir dist",
     "build-js": "tsup lib/index.ts --dts",
-    "build": "pnpm run lint && pnpm run build-dom-scripts && pnpm run build-js && pnpm run build-types",
+    "build": "pnpm run lint && pnpm run gen-version && pnpm run build-dom-scripts && pnpm run build-js && pnpm run build-types",
+    "gen-version": "tsx scripts/gen-version.ts",
     "prepare": "pnpm run build",
     "lint": "pnpm run prettier:fix && pnpm run eslint",
     "release": "pnpm run build && changeset publish",

scripts/gen-version.ts

@@ -0,0 +1,18 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+
+type PackageJson = { version: string };
+
+const pkgPath = join(__dirname, "..", "package.json");
+const pkg: PackageJson = JSON.parse(readFileSync(pkgPath, "utf8"));
+
+const fullVersion: `${string}` = pkg.version;
+
+const banner = `/**
+ * AUTO-GENERATED — DO NOT EDIT BY HAND
+ *  Run \`pnpm run gen-version\` to refresh.
+ */
+export const STAGEHAND_VERSION = "${fullVersion}" as const;
+`;
+
+writeFileSync(join(__dirname, "..", "lib", "version.ts"), banner);

types/stagehandErrors.ts

@@ -1,4 +1,5 @@
 import { ZodError } from "zod";
+import { STAGEHAND_VERSION } from "../lib/version.js";
 
 export class StagehandError extends Error {
   constructor(message: string) {
@@ -11,7 +12,7 @@ export class StagehandDefaultError extends StagehandError {
   constructor(error?: unknown) {
     if (error instanceof Error || error instanceof StagehandError) {
       super(
-        `\nHey! We're sorry you ran into an error. \nIf you need help, please open a Github issue or reach out to us on Slack: https://stagehand.dev/slack\n\nFull error:\n${error.message}`,
+        `\nHey! We're sorry you ran into an error. \nStagehand version: ${STAGEHAND_VERSION} \nIf you need help, please open a Github issue or reach out to us on Slack: https://stagehand.dev/slack\n\nFull error:\n${error.message}`,
       );
     }
   }