debugger: fix unhandled error in setBreakpoint

[bajtos]

Fix Interface.setBreakpoint() to correctly handle an attempt to set a
breakpoint in the current script when there is no current script. This usually
happens when the debugged process is not paused.

Close #6453

@bnoordhuis Please review. Is it worth adding a unit test for this change? It's more than just adding few lines to test/simple/test-debugger-repl.js, a new test fixture is needed.

[Nodejs-Jenkins]

Thank you for contributing this pull request! Here are a few pointers to make sure your submission will be considered for inclusion.

Commit bajtos/node@357f4bb has the following error(s):

• Commit message line too long: 3

The following commiters were not found in the CLA:

• Miroslav Bajtos

You can fix all these things without opening another issue.

Please see CONTRIBUTING.md for more information

[bajtos]

@tjfontaine @trevnorris Who is the best person to review this pull request, now that Ben is gone?

[trevnorris]

There a test you could include?

[tjfontaine]

unfortunately the test would probably be flakey, this seems fairly reasonable, I'm not necessarily thrilled with the message in general, the question doesn't seem necessary?

[bajtos]

@tjfontaine I'm not necessarily thrilled with the message in general, the question doesn't seem necessary?

Shall I rephrase? Cannot determine the current script, make sure the debugged process is paused.

Or keep it short but not very helpful? Cannot determine the current script.

@trevnorris There a test you could include?

I can write a new one from scratch, but as TJ pointed out, it may cost more on maintenance that it will bring back as regression guard. I don't mind either way -i f you think there should be a test then I'll add it.

[bajtos]

@tjfontaine @trevnorris ping, what changes are needed to get this patch landed?

[chrisdickinson]

Shall I rephrase? Cannot determine the current script, make sure the debugged process is paused.

I'd say this would be an acceptable way to phrase the error. If there are no strong objections by EOD tomorrow, I'll merge.

[bajtos]

@chrisdickinson thank you. I have rebased the commit on top of the current master and reworded the message.

[tjfontaine]

Thanks @chrisdickinson landed this in e93ff4f