Editing a message containing a list with an empy last value will crash the client

[Thunderhelm]

Describe the bug

When attempting to edit a message containing a formatted ordered or unordered list, if the final entry in the list contains no text, the client will crash with the following error:

Error: Cannot get the end point in the node at path [1] because it has no end text node.
    at oot (https://app.sable.moe/assets/index-CyIDp8UT.js:115497:32)
    at Object.point (https://app.sable.moe/assets/index-CyIDp8UT.js:116763:16)
    at Object.point (https://app.sable.moe/assets/index-CyIDp8UT.js:114171:16)
    at Cit (https://app.sable.moe/assets/index-CyIDp8UT.js:115145:25)
    at Object.end (https://app.sable.moe/assets/index-CyIDp8UT.js:116643:16)
    at Object.end (https://app.sable.moe/assets/index-CyIDp8UT.js:114068:16)
    at https://app.sable.moe/assets/index-CyIDp8UT.js:115928:27
    at Fot (https://app.sable.moe/assets/index-CyIDp8UT.js:115713:7)
    at Object.withoutNormalizing (https://app.sable.moe/assets/index-CyIDp8UT.js:116847:16)
    at Object.withoutNormalizing (https://app.sable.moe/assets/index-CyIDp8UT.js:114213:9)

This happens whether or not markdown is enabled.

Reproduction

1. enter any text chat
2. send a message formatted like either of the following

test
• test
•

test
1. test
2. 

3. attempt to press the edit widget on the message

Expected behavior

The client would handle the final value being empty by letting it remain empty when initially editing.

Platform and versions

1. OS: Linux Mint 22.3 - Xfce
2. Browser: Sable's electron client (specifically from the README hyper-link)
3. Sable version: 0.5.7 (c927bc7b)
4. Matrix homeserver: bearware.dev (running c10y)

Additional context

No response