i3bar: null pointer dereference when encountering strings instead of objects in json protocol

[Ferdi265]

I'm submitting a…

[x] Bug
[ ] Feature Request
[ ] Documentation Request
[ ] Other (Please describe in detail)

Current Behavior

i3bar crashes when encountering invalid input, such as when encountering a string instead of an object representing a block.

Core Dump: https://drive.google.com/open?id=1AbmEqk5rEXIsDYvd9U-yiA1dPibCnIpj

Expected Behavior

i3bar should not crash.

The invalid input should be reported as an error.

Alternatively, strings could be accepted and interpreted as plain text blocks. (swaybar does this)

Reproduction Instructions

use this i3 config and status command:
https://gist.github.com/Ferdi265/dc6c2ebbd5d21970df02caa7f5685827

Environment

Output of i3 --moreversion 2>&-:

Binary i3 version:  4.17.1 (2019-08-30) © 2009 Michael Stapelberg and contributors
Running i3 version: 4.17.1 (2019-08-30) (pid 61803)
Loaded i3 config: /home/yrlf/.config/i3/config (Last modified: Tue 22 Oct 2019 22:00:39 CEST, 890 seconds ago)

The i3 binary you just called: /usr/bin/i3
The i3 binary you are running: i3

- Linux Distribution & Version: ArchLinux
- Are you using a compositor (e.g., xcompmgr or compton): No

[i3bot]

I don’t see a link to logs.i3wm.org. Did you follow https://i3wm.org/docs/debugging.html? (In case you actually provided a link to a logfile, please ignore me.)

[Airblader]

Alternatively, strings could be accepted and interpreted as plain text blocks.

So does i3bar if you specify that you want that version of the protocol. It's essentially deprecated, though.

I agree that i3bar should not crash, though I think exiting with an error is acceptable. The status program should never generate invalid protocol messages.