Ensure query error messages in popups are succinct

[aeisenberg]

Is your feature request related to a problem? Please describe.

When the query server throws an exception while running a query, it is easy to ignore or be unaware of it. In many cases, the query run still returns results, just not in the expected format. Users can be confused by this.

Exceptions are sent to the output log, but there is no notification that an error has occurred at all. If the user is not monitoring the output log, then they will not be aware that an error has occurred at all.

For example, running with invalid query metadata can send an exception like this to the console:

A fatal error occurred: Could not process query metadata.
Error was: No query kind specified(NO_KIND_SPECIFIED).
[2021-01-18 14:08:15] Exception caught at top level: Could not process query metadata.
                      Error was: No query kind specified(NO_KIND_SPECIFIED).
                      com.semmle.cli2.bqrs.InterpretCommand.executeSubcommand(InterpretCommand.java:123)
                      com.semmle.cli2.picocli.SubcommandCommon.executeWithParent(SubcommandCommon.java:414)
                      com.semmle.cli2.execute.CliServerCommand.lambda$executeSubcommand$0(CliServerCommand.java:67)
                      com.semmle.cli2.picocli.SubcommandMaker.runMain(SubcommandMaker.java:201)
                      com.semmle.cli2.execute.CliServerCommand.executeSubcommand(CliServerCommand.java:67)
                      com.semmle.cli2.picocli.SubcommandCommon.call(SubcommandCommon.java:430)
                      com.semmle.cli2.picocli.SubcommandMaker.runMain(SubcommandMaker.java:201)
                      com.semmle.cli2.picocli.SubcommandMaker.runMain(SubcommandMaker.java:209)
                      com.semmle.cli2.CodeQL.main(CodeQL.java:91)

Describe the solution you'd like

It would be useful if some relevant part of this message was put in a message dialog so that users would be aware that some unexpected behaviour occurred.

I imagine that we'd want to do some regex matching on messages coming in to find things that look like errors. If the regex matches, then we place that message (or part of the message) into a popup.

[edoardopirovano]

Hmm, on my install I already seem to get a popup advising me to look at the log when an error has occurred in the CLI. For instance, see the screenshot below for what happens when I run a query with invalid metadata (as in your example). Could this be something to do with my configuration? Or are there errors in the query server that do not result in a CLI error that we would like to be outputting? If so, could you give me an example of one and I'm happy to work on this issue then?

[aeisenberg]

Right. This was partially addressed in #770. I still think there's room for improvement. The current error message in this case is too large for the popup. In this case, it would be great if we could just show the first two lines of the error message in the popup, like this:

Interpreting query results failed: A fatal error occurred: Could not process query metadata.
Error was: No query kind specified [NO_KIND_SPECIFIED]

Though, we also need to be careful because not all error messages are formatted like this.

I'll update the issue title to reflect this.

[edoardopirovano]

Addressed in #792.