[Bug]: Deno Deploy dashboard does not run if mixpanel.ts script is blocked by ad blocker

### Problem description

When I try opening the Deno Deploy dashboard with Ghostery running, the `mixpanel.ts` script is blocked from loading. This causes subsequent JS error which prevents the page from functioning correctly after login:

### Steps to reproduce

1. Enable URL blocking for `https://dash.deno.com/utils/mixpanel.ts`
2. Reload the page
3. See broken page

### Expected behavior

Ideally ad blockers should not detect false positives if `mixpanel.ts` ends up not being a tracker. If it is, it might be worth handling failed script loading in case it isn't a false positive.

### Environment

Latest stable Chrome on Windows, latest Ghostery extension.

### Possible solution

_No response_

### Additional context

_No response_

Start by reproducing the Deno Deploy dashboard failure while blocking https://dash.deno.com/utils/mixpanel.ts, then trace how the dashboard handles that script after login. Done means the dashboard remains functional when mixpanel.ts is blocked, with the relevant regression behavior covered by the project's existing checks.

Written by the indexing model from the issue text.