feat: add stack to stacktraceless "exceptions"

[daibhin]

Changes

Why miss out on a stack trace if you call captureException with a string?

This changes things to throw an error to capture the current stack trace and strips the final frame (e.g. inside our captureException function)

[vercel]

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Name	Status	Preview	Updated (UTC)
posthog-js	✅ Ready (Inspect)	Visit Preview	Oct 16, 2024 8:37am

[daibhin]

This is a superior approach but I couldn't get it to work. The function name I was seeing was t.value in the stack trace. Perhaps there's some Javascript function construction magic needed to ensure the function name gets caught in the stack. Open to any thoughts if people have them?

[neilkakkar]

probably because array.js is minified? Or the loaded extensions are if we're using the npm version of main package..

[daibhin]

Probably true - very meta given our current work 😂

[github-actions]

Size Change: +2.05 kB (+0.07%)

Total Size: 2.83 MB

Filename	Size	Change
dist/all-external-dependencies.js	192 kB	+244 B (+0.13%)
dist/array.full.js	355 kB	+309 B (+0.09%)
dist/array.full.no-external.js	354 kB	+309 B (+0.09%)
dist/array.js	169 kB	+65 B (+0.04%)
dist/array.no-external.js	168 kB	+65 B (+0.04%)
dist/exception-autocapture.js	11.4 kB	+247 B (+2.22%)
dist/main.js	170 kB	+65 B (+0.04%)
dist/module.full.js	355 kB	+309 B (+0.09%)
dist/module.full.no-external.js	354 kB	+309 B (+0.09%)
dist/module.js	169 kB	+65 B (+0.04%)
dist/module.no-external.js	168 kB	+65 B (+0.04%)

ℹ️ View Unchanged

Filename	Size
dist/external-scripts-loader.js	2.35 kB
dist/recorder-v2.js	111 kB
dist/recorder.js	111 kB
dist/surveys-preview.js	59.8 kB
dist/surveys.js	66 kB
dist/tracing-headers.js	8.36 kB
dist/web-vitals.js	10.3 kB

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[neilkakkar]

do we need to update the type here as well now?

[daibhin]

I was torn... technically I'd still like people to send us errors but it is a little misleading to ourselves to think that the input will always be an error. What I really want is to type it as unknown but for a user to be shown Error as the type

[neilkakkar]

nice

[neilkakkar]

oh wait, this doesn't work well for the case where currently we're not seeing stack traces, it's a different captureException function that's called: https://github.com/PostHog/posthog-js/blob/master/src/extensions/exception-autocapture/index.ts#L76

[daibhin]

@neilkakkar you're right, this actually only fixes the issue where the stack trace is missing after a user manually called captureException with a string / object that does not have a stack

The global onerror and unhandledrejection you linked should always have an error and thus not need a synthetic exception The captureException you linked is actually the callback used in the wrapped functions (here and here) to parse that error.

The case where the stack trace is missing from a genuine error is probably more likely related to this issue: https://sentry.io/answers/script-error/ (I'm going to try recreating this now, I would suspect that the script just needs to be loaded anonymously)