Error in npm run build in plugin

[arnabneogi86]

While running npm run build in the plugin, it is throwing error:

[email protected] build-esm
BABEL_OUTPUT=esm babel src --extensions ".ts,.tsx,.js,.jsx" --copy-files --out-dir esm

'BABEL_OUTPUT' is not recognized as an internal or external command,
operable program or batch file.

and the esm folder is not created.

On running
BABEL_OUTPUT=esm babel src --extensions ".ts,.tsx,.js,.jsx" --copy-files --out-dir esm

It is throwing error:
src\index.ts -> esm\index.js
SyntaxError: src/plugin/buildQuery.ts: Unexpected token, expected , (21:43)
19 | import { buildQueryContext, QueryFormData } from '@superset-ui/core';
20 |

21 | export default function buildQuery(formData: QueryFormData) {
| ^
22 | return buildQueryContext(formData, baseQueryObject => [
23 | {
24 | ...baseQueryObject,

Am I missing something?

followed the exact steps