Bun panic: Bus error (SIGBUS) on main thread, v1.4.0

Description

Claude Code crashed with a Bun runtime panic while working in a project:

panic(main thread): Bus error at address 0x12A49BE30

Environment

• Claude Code version: 2.1.201
• Bun version: 1.4.0 (bundled with Claude Code)
• OS: macOS 26.6 (BuildVersion 25G72)
• Arch: arm64 (Apple Silicon)
• Kernel: Darwin 25.6.0

Context

• Project directory is on an external PCI-Express/Thunderbolt-attached APFS volume (not a network share, not USB), mounted as fixed (non-removable) media.
• Immediately prior to the crash, a large batch of file I/O had just completed in the session (a content-extraction pipeline had staged hundreds of images/manifests to local disk under the project directory).
• No repro steps identified yet — occurred once, did not recur on restart.

Notes

A SIGBUS during a Bun main-thread panic is often associated with an mmap'd file being truncated/invalidated mid-read, or an I/O stall on the backing volume. Flagging in case this correlates with other reports of Bun/Claude Code crashes on external-volume or high file I/O workloads.