[BUG] Crash on session resume: "null is not an object (evaluating 'q.split')" in diff/edit renderer (regression of #38633)

Preflight Checklist

• [x] I have searched existing issues and this appears to be a regression of previously-closed reports (#37454, #38633, #38869)
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

Restarted my computer while a session was open. When the terminal/tab reopened and resumed the session, the CLI crashed immediately with:

ERROR  null is not an object (evaluating 'q.split')

The stack trace points into the diff/Edit-tool-result renderer (minified, but the crashing function receives file content and calls .split() on it without a null guard):

 - Ie7 (/$bunfs/root/src/entrypoints/cli.js:3212:1690)
 - LV7 (/$bunfs/root/src/entrypoints/cli.js:2663:6380)
 - aA (/$bunfs/root/src/entrypoints/cli.js:681:20998)
 - Rf (/$bunfs/root/src/entrypoints/cli.js:681:39542)
 - $YH (/$bunfs/root/src/entrypoints/cli.js:681:50236)
 - IV (/$bunfs/root/src/entrypoints/cli.js:681:86921)
 - Eo_ (/$bunfs/root/src/entrypoints/cli.js:681:85884)
 - lEH (/$bunfs/root/src/entrypoints/cli.js:681:85706)
 - w7_ (/$bunfs/root/src/entrypoints/cli.js:681:82457)
 - sH (/$bunfs/root/src/entrypoints/cli.js:681:6489)
 - async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:16606:279)

This looks like the same root cause as #37454, #38633, and #38869: a renderer calls originalFile.split('\n') (or similar) without checking for null, which throws when the original file content isn't available (e.g. a file that no longer exists, or a snapshot that wasn't persisted). Those issues were closed/fixed previously, but the crash is back on the current version.

What Should Happen?

Resuming a session should render previous tool results gracefully even when original file content is unavailable, using a null-safe access (q?.split(...)) or a guard/fallback, instead of crashing the whole CLI.

Steps to Reproduce

1. Have an active Claude Code session that includes file Edit/Write tool calls.
2. Restart the computer without cleanly exiting the session.
3. Reopen the terminal and resume the session (session auto-resumed on tab reopen in my case).
4. CLI crashes immediately with null is not an object (evaluating 'q.split') before rendering the conversation.

Claude Code Version

2.1.215

Platform

macOS 26.5.1 (BuildVersion 25F80), Darwin 25.5.0

Is this a regression?

Likely yes — see #37454, #38633, #38869, which describe the identical crash signature and were previously closed.