Claude Code 2.1.286〜2.1.288 hidden-failure traps: three fix points

The author describes the silent-failure problem as the single biggest time sink when writing Claude Code Mods, because there is no error output and nothing conspicuous in the logs. Three causes are separated out, and the recommended order of inspection runs top to bottom: static validation of the module source at load time, missing pieces in the hook execution environment, and render trees that break component conventions.

The second cause is a runtime that is neither Node nor a browser, so copying code from npm packages can read process.env at import time and kill the whole Mod. The author worked around this by placing a file-local substitute for process and setTimeout at the top of that file. The other limit is time: a hook runs for at most 10 seconds, and a permission guard (tool.check) doing heavy work will silently let requests through.

The third cause is the hardest to notice, because Claude Code simply draws its own display again when the tree returned by ui.render does not conform. Values such as undefined, autoFocus: false, Button's plain: false, and a missing source or alt on Svg all fall outside the rules, so the author wraps component construction in a single strip function that drops undefined entries before passing props on.