Limiting session log size can break on 19.0

[dzaima]

Describe the issue you are having

The session log may be left in a broken state if truncated with 19.0.

How do you reproduce the issue?

1. Set RIDE "Session log size" to 1000 lines
2. RIDE_SPAWN=/opt/mdyalog/19.0/64/unicode/mapl /usr/bin/ride-4.5
3. Execute ⍳2000 1
4. Observe that the └ continues. Restarting RIDE will result in the inability to run anything.

IDE:
  Version: 4.5.4097
  Electron: 26.6.9
  Chrome: 116.0.5845.228
  Node: 18.16.1
  Platform: Linux x86_64
  Date: 2024-02-23 15:24:25 +0100
  Git commit: 9fb313638328832b51012bd75b2523a8d97f4509
  Preferences:{
    "defaultConfig":"v19.0",
    "kbdLocale":"en_US",
    "sessionLogSize":"1000"
  }

Interpreter:
  Version: 19.0.48958
  Platform: Linux-64
  Edition: Unicode/64
  Date: Mar  6 2024 at 11:16:30