Update regex pattern in shouldDropLine

[walseb]

Ref: #183

I haven't had time to try this change yet. Perhaps there are issues with it.

[walseb]

I have tried this change out briefly, but now I sometimes get errors with this:

Could not find module ‘MV’.
 Use :set -v to see a list of the files searched for.
| [GHC-87110]

What's abnormal is this: | [GHC-87110]

Which isn't even shown in the GHCIWatch output for some reason.

I will try adjusting the regexp by adding a check for whether BOL is to the left of the bar.

[walseb]

That didn't fix it. Is | [GHC-87110] supposed to be there, and I just haven't noticed it before?

It seems to be appearing in the beginning of all errors now.

[josephsumabat]

I've wanted to fix the parsing for a bit (we actually have a different set up on our internal fork..) but if you can get this tested working I'll happily merge.

[walseb]

I have been testing this over the last few days with no issues.

I suppose the BOL check in the regexp might be unnecessary. I have never seen the error line preview bars appear at the beginning of a line:
[^\s]+\|[\s$]+

But it might be possible, and I don't see a reason to remove it as it doesn't conflict with anything that I know of (especially as the last solution would capture ANY bars used in the line at all).

[walseb]

I forgot to mention:

That didn't fix it. Is | [GHC-87110] supposed to be there, and I just haven't noticed it before?
It seems to be appearing in the beginning of all errors now.

Regarding that, | [GHC-87110] appears even without my changes. I believe it's actually the error code. As for why it appears at the end of errors, I don't know, but it's not relevant to this issue I believe.