hevm: tty: skip null src maps when jumping with shift+n

[d-xo]

Description

I think this fixes #686, but since the source map format and parser are very mysterious to me I'm not really sure that I've done the right thing.

Afaict the issue was that we sometimes get a sourcemap back from currentPosition that looks like this:

Just (SM {srcMapOffset = -1, srcMapLength = -1, srcMapFile = -1, srcMapJump = JumpRegular, srcMapModifierDepth = 0})

Which is treated as distinct by the check in isNextSourcePosition. I'm assuming the -1 in this case is a sentinel value meaning the given source pc does not have a corresponding position in the provided source map? Perhaps there is a cleaner fix here where we make this position unrepresentable? @MrChico thoughts?

cc @transmissions11 for testing.

Checklist

• tested locally
• added automated tests
• updated the docs
• updated the changelog

[transmissions11]

yayy tysm for the fix! doesn't seem to work for me yet sadly

[transmissions11]

btw just to clarify the reproduction cases a bit more:

• it comes up with shift + N and shift + P
• it does not come up with control + n but does come up sometimes with control + p

[transmissions11]

if you want a repo to try it on, can follow the getting started instructions on the README of the this repo and debug the first test the menu shows you: https://github.com/rari-Capital/vaults

[transmissions11]

the issue is super pronounced in that repo because hevm doesn't seem to recognize the Vault contract at all (hence why they have no label in the debugger), so no sourcemaps can be pulled for it. will file a separate issue for that as well (still think this is a fix we should implement nonetheless)

[d-xo]

yayy tysm for the fix! doesn't seem to work for me yet sadly

sad, I was testing in dss and I thought I'd fixed this. will take a look at vaults and see if I can figure out what's going on.

the issue is super pronounced in that repo because hevm doesn't seem to recognize the Vault contract at all (hence why they have no label the debugger), so no sourcemaps can be pulled for it. will file a separate issue for that as well

hmmmm, yeah this is bad, issue would be great 👍

still think this is a fix we should implement nonetheless

agree

[MrChico]

c-N uses the isNextSourcePositionWithoutEntering function, the fix here touches only isNextSourcePosition.