fix(nextjs): Fix error logging

[lobsterkatie]

This PR makes two changes to the function which wraps the native error logger:

• Calls the original method rather than returning a bound copy of it
• Refactors it to be a real (non-arrow) function, so that the original this (a Server instance) isn't overwritten by the this (global) present when the function is defined

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	20.63 KB (+0.01% 🔺)
@sentry/browser - Webpack	21.5 KB (0%)
@sentry/react - Webpack	21.53 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	27.92 KB (0%)