Agent extension api (#5281)

Co-authored-by: Douwe Osinga <douwe@squareup.com>

ui/desktop/src/utils/conversionUtils.ts

@@ -11,3 +11,13 @@ export async function safeJsonParse<T>(
     throw error;
   }
 }
+
+export function errorMessage(err: Error | unknown, default_value?: string) {
+  if (err instanceof Error) {
+    return err.message;
+  } else if (typeof err === 'object' && err !== null && 'message' in err) {
+    return String(err.message);
+  } else {
+    return default_value || String(err);
+  }
+}

ui/desktop/src/utils/costDatabase.ts

@@ -1,6 +1,6 @@
 // Import the proper type from ConfigContext
 import { getApiUrl } from '../config';
-import { safeJsonParse } from './jsonUtils';
+import { safeJsonParse } from './conversionUtils';
 
 export interface ModelCostInfo {
   input_token_cost: number; // Cost per token for input (in USD)

ui/desktop/src/utils/githubUpdater.ts

@@ -4,7 +4,7 @@ import * as fs from 'fs/promises';
 import * as path from 'path';
 import * as os from 'os';
 import log from './logger';
-import { safeJsonParse } from './jsonUtils';
+import { safeJsonParse } from './conversionUtils';
 
 interface GitHubRelease {
   tag_name: string;