Error "Cannot read property 'map' of null" when attempting to read empty object

[philrz]

Repro is with Brim commit 297df23 talking to zqd commit 232b748.

Consider the following NDJSON containing an empty object.

$ cat empty.ndjson 
{"emptyarray": {}}

When attempting to import it into Brim, I see the following error:

However, zq has no problem reading it.

$ zq -z empty.ndjson 
{emptyarray:{}}

[philrz]

Verified in Brim commit 19dd931.

It's not much to look at, but now dragging the NDJSON into the app, there's no longer an error.

Verify.mp4

Notice that the name of the object is not visible in the Log Detail. I've added a note at #1245 (comment) to make sure we cover this when we address the wider problem of presenting complex data types in Brim.

Thanks @jameskerr!