Launching from Finder or the Dock leaves the main process with stdio that has
no reader. Writing there fails asynchronously with EPIPE from inside the stream
machinery, and with no `error` listener Node escalates it to an uncaught
exception — which Electron shows as "A JavaScript error occurred in the main
process".
This is reachable in ordinary use: the sidecar exit handler logs a line every
time a sidecar dies, so any crashed or killed sidecar could raise that dialog.
Guarding that one call site would not help, since the main process has ~25
console call sites and all of them write to the same two streams. A try/catch
at the call site cannot help either, because the throw happens off-stack.
Install the guard on stdout/stderr before anything logs. Losing a diagnostic
line is acceptable; killing the user's session over one is not — real
diagnostics already persist to a file through appendHostDiagnostic.
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