Crash: null is not an object (evaluating 'z.isMemoryWrite') in message collapsing

Summary

Claude Code crashed ungracefully with ERROR null is not an object (evaluating 'z.isMemoryWrite'). The crash interrupted an active long-running session that had been running cleanly for hours.

Version

• claude CLI: 2.1.112 (Claude Code)
• Linux x86_64 (Ubuntu 6.8.0-110-generic)
• Shell: bash

Error trace (top frames)

jJ7 (/$bunfs/root/src/entrypoints/cli.js:4779:2464)
<anonymous> (/$bunfs/root/src/entrypoints/cli.js:6260:14646)
TT (/$bunfs/root/src/entrypoints/cli.js:477:30111)
...

Root cause (from the minified source)

In A51(H, $):

function A51(H,$){
  if(H.type==="assistant"){
    let q=H.message.content[0], K=cK$(q,$);
    if(K && q?.type==="tool_use") return {name:q.name, input:q.input, ...K}
  }
  if(H.type==="grouped_tool_use"){
    let q=H.messages[0]?.message.content[0];
    let K=cK$(q ? {type:"tool_use", name:H.toolName, input:q.input} : void 0, $);
    if(K && q?.type==="tool_use") return {name:H.toolName, input:q.input, ...K}
  }
  return null   // ← can return null
}

In jJ7, the caller:

let z = A51(f, $);
if (z.isMemoryWrite) { ... }  // ← crashes here when z === null

The caller is inside the branch where O51(f, $) is true (collapsible tool use) but A51 can still return null — e.g. if the tool classification (cK$) returns falsy for the wrapped content, or if q?.type !== "tool_use".

Context of the crash

I was in a long session working on a knowledge-base pipeline. Many tool uses had already happened. The crash hit while I was running a batch of Bash/Edit tool calls via an ongoing conversation. The session had been running for hours with high message density. Nothing unusual about the last tool call — just a normal Bash invocation. The crash was unrecoverable: the terminal dumped the full minified stack and exited.

Expected behavior

Null check on z before accessing z.isMemoryWrite, or make A51 always return a shape-complete object (with isMemoryWrite: false default) instead of null.

Suggested fix

In jJ7, where A51's result is consumed:

let z = A51(f, $);
if (!z) continue;   // or handle the null branch
if (z.isMemoryWrite) { ... }

Or equivalently, make A51 return a default object instead of null:

return { name: "", input: null, isMemoryWrite: false, isAbsorbedSilently: false, ... };

Impact

• Long sessions are at risk of dying mid-work due to one unclassifiable tool_use message.
• No graceful recovery — the whole CLI exits. Users lose session state, in-flight background tasks may orphan (in my case an overnight pipeline run).