fix(react): Remove unnecessary null in FallbackRender's error type

[lobsterkatie]

We already know error exists because of the if (error) check.

Fixes #2892.

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	17.69 KB (0%)
@sentry/browser - Webpack	18.51 KB (0%)
@sentry/react - Webpack	18.51 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	23.47 KB (+0.01% 🔺)

[twavv]

Similarly, componentStack will never be non-null, though I think that would fail type-checking right now.

A good solution might just to be to store all of the information about the error in one single state variable?

interface State {
  errorInfo: null | {
    error: Error
    componentStack: string
    ...
  }
}

// instead of
interface State {
  error: Error | null
  componentStack: string | null
}

[kamilogorek]

The original issue fix looks good, you can approach the issue from @travigd either here or separate PR.

[lobsterkatie]

@travigd - That's not a bad idea in the long run, but for the moment we're going to hold off, just to get this in without further complication.

If you're interested and can do it in such a way that it won't be a breaking change for anyone using it now, we welcome PRs! 🙂