docs(examples): fix error connection handling

[chornos13]

When there's an error while connect to mongodb (timeout for example), it will be cached and need to restart next.js, by handling the error correctly (clear cached promise) it will try to reconnect to mongodb if the function is called again

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have a helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have a helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running pnpm lint
• The "examples guidelines" are followed from our contributing doc

[ijjk]

Thanks!