Feat: Allow node stackwalk in Electron renderer

[timfish]

Related to: getsentry/sentry-electron#308

This PR:

• Moves @sentry/node functions eventFromException and eventFromMessage out of backend and into their own file much like in the browser SDK.
• Re-exports them for use in @sentry/electron
• Adds readFile as a parameter in the parser functions

Why is this funky readFile stuff required?

The Electron renderer may or may not have access to node functionality. If nodeIntegration is enabled, full node is available. If nodeIntegration is disabled and a bundler is being used, it will complain that fs cannot be found/is unavailable. With this PR we would just not pass readFile when the stack parser is called from the Electron renderer and no source files will be read.

What are the alternatives?

• Have different entry points in @sentry/electron depending on nodeIntegration (ie. init and initWithNode)
• Inform those using bundlers that they need to add fs to externals
• Add a NodeIntegration sentry integration that "patches" in this functionality?
• Any other ideas?

[timfish]

I've also got a branch that uses dynamicRequire(module, 'fs') but that has the significant downside that source file loading will no longer function if a bundler is being used.

[kamilogorek]

Would it maybe be possible to just bail out if fs is not available?

functiontryToReadFile(filename,resolve): void{try{const{ readFile }=require('fs');// move previous logic here}catch(_e){returnnull;}}

Although totally valid, the implementation from this PR adds a lot of indirection which is kinda hard to follow.

[timfish]

Would it maybe be possible to just bail out if fs is not available?

Any usage of require('fs') would be picked up by bundlers and throw errors which would force everyone to add fs to externals.

[timfish]

I've refactored this to be a bit better in that rather than passing around a ref to readFile, the source reading is now in it's own file and I pass around a ref to readFilesAddPrePostContext.

It would still probably be better to refactor the source reading out of parseStack entirely and into its own step that could be applied to the event after.

So in @sentry/node it would be used like this:

publiceventFromException(exception: any,hint?: EventHint): PromiseLike<Event>{
const event=eventFromException(this._options,exception,hint);returnaddSourcesToEvent(event);}

And in @sentry/electron you would simply skip adding the sources:

publiceventFromException(exception: any,hint?: EventHint): PromiseLike<Event>{returneventFromException(this._options,exception,hint);}

Do you think the unit tests are up to supporting me through that kind of refactor? 🙂

[timfish]

Closing in favour of #3729