Simplify error handling in build-dashboard.js

[coderabbitai]

As discussed in PR #3304 (comment), @akshatnema agreed to improve the error handling by throwing errors directly instead of using Promise.reject(e); in the build-dashboard.js script.

We should update the error handling code to throw errors directly, making the asynchronous functions more idiomatic and easier to read.

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[lakshaydewan]

Working on same will be raising a PR soon..

[lakshaydewan]

PR #3310 fixes the issue needs a review though..