fix(web-vitals): [v7] Check for undefined navigation entry

[AbhiPrasad]

Backport of #11311

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	80.48 KB (+0.04% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	71.47 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing, Replay with Canvas) - Webpack (gzipped)	75.48 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	65.1 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	35.41 KB (+0.02% 🔺)
@sentry/browser (incl. browserTracingIntegration) - Webpack (gzipped)	35.29 KB (+0.01% 🔺)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	31.52 KB (+0.09% 🔺)
@sentry/browser (incl. sendFeedback) - Webpack (gzipped)	31.53 KB (+0.09% 🔺)
@sentry/browser - Webpack (gzipped)	22.74 KB (0%)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	78.59 KB (+0.05% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	69.97 KB (0%)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	35.77 KB (+0.01% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	25.17 KB (0%)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	220.31 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	108.12 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	75.48 KB (0%)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	39 KB (+0.01% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	71.96 KB (+0.01% 🔺)
@sentry/react - Webpack (gzipped)	22.77 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	89.81 KB (+0.01% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	53.95 KB (+0.01% 🔺)
@sentry-internal/feedback - Webpack (gzipped)	17.3 KB (+0.15% 🔺)