Break on conditional exceptions in node debugger

[cdaringe]

ref 1

Problem

It is often challenging to narrow the emitter of an exception using node + vscode tooling. For example, many node internals throw exceptions often, as do userland libraries. skipFiles is a noble attempt that helps to aide with this problem, but requires that the user collect possibly large domains of possible paths up front, where often it is unknown whom is responsible for emitting an exception. As suggested in similar threads, I cannot reasonably use <node_internals> in my skipFiles, as code that is-on-the-fly compiled is put into VM scripts, and is thus ignored. Further, in some cases, i'm OK breaking inside of internals. During daily debugging, I have knowledge about an exception (perhaps stderr output from a prior run), that I really want to hone in on--and thus want a conditional breakpoint to rapidly narrow my search.

This feature would add a mechanism like conditional breakpoints, but just to exceptions. Perhaps it would be as follows:

• select [x] All exceptions in the debugger
• right click => add condition
• observe placeholder prompt "err =>
• user fills in function
• user hits enter to save the function

err => err && err.message.match(/react/)

the need for a lamba here is because the exception of course isn't otherwise in scope--providing a function lets us introspect the error.

[connor4312]

I've decided this is best implemented as a formal DAP feature and opened a proposal there: microsoft/debug-adapter-protocol#137 Moving this issue to backlog until that's resolved. (September release at the soonest, as our iteration ends on Monday)

[rrmistry]

@connor4312 , would conditional breakpoints be a separate DAP feature request?

I tried but couldn't find an existing issue (open / closed) for this exact feature request.

[connor4312]

Conditional breakpoints are already supported in DAP and in VS Code https://code.visualstudio.com/docs/editor/debugging#_conditional-breakpoints

[rrmistry]

Never mind. I found it. For anyone else on the same path, the way to set conditional breakpoints is right click the breakpoint and select Edit Breakpoint:

[connor4312]

This is implemented in VS Code in #111227, which debuggers will need to adopt to enable; I'll use this feature request to track adding to the JS debugger.

[connor4312]

This will be in the next nightly build. The current exception is in the error variable, for example:

[cdaringe]

I am thrilled! I'll be installing nightly immediately to try this out. @weinand and @connor4312, deep gratitude for this killer feature

[isidorn]

@connor4312 adding the on-testplan since this should be covered by a test plan item, thus no further verification should be needed if I am nto mistaken.