improve AggregateError message

Author: mbostock

bin/query.ts

@@ -55,7 +55,7 @@ export default async function run(args?: string[]): Promise<void> {
     await writeFile(cachePath, JSON.stringify(results, replace));
     console.log(join(values.root, cachePath));
   } catch (error) {
-    console.error(String(error));
+    console.error(getErrorMessage(error));
     process.exit(1);
   }
 }
@@ -65,3 +65,12 @@ export default async function run(args?: string[]): Promise<void> {
 function replace(this: {[key: string]: unknown}, key: string, value: unknown): unknown {
   return this[key] instanceof Date ? Date.prototype.toJSON.call(this[key]) : value;
 }
+
+function getErrorMessage(error: unknown): string {
+  return error instanceof Error &&
+    "errors" in error && // AggregateError
+    Array.isArray(error.errors) &&
+    error.errors.length > 0
+    ? String(error.errors[0])
+    : String(error);
+}