fix: prevent native crash when a transformer worklet throws#14
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RunTransformer called the transformer through runSync and used the result unconditionally. In release builds runSync is a raw jsi Function::call, so an error thrown by the worklet propagated as jsi::JSError through the UIKit text input delegate / Android TextWatcher and aborted the app. In debug builds the worklets call guard reports the error to LogBox and returns undefined, so the following asObject call threw with the same result. Catch jsi errors around the transformer invocation and result extraction, log them to the UI runtime console, and fall back to leaving the input untransformed. Add a throwing transformer card to the example app to exercise the path.
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Description
A transformer worklet that throws kills the app natively: the error propagates uncaught from
RunTransformerinto the iOStextInputDidChangedelegate / Android JNI TextWatcher and aborts with SIGABRT on the first keystroke. In release builds worklets'runSynccalls the function raw (source); in debug the call guard returnsundefinedand the followingasObject()throws instead. This is easy to hit from user code — any transformer returning an out-of-bounds selection makesvalidateSelectionthrow by design.Solution
Never let a transformer error cross the native boundary, and surface it instead of swallowing it. The worklet call and result extraction are wrapped in try/catch; caught errors are logged (LogBox via the worklets call guard in debug,
console.erroron the UI runtime in release) andRunTransformerreturnsstd::nullopt, which both platforms already treat as "no transform" — the input keeps the raw text.The example app has a new "Throwing Transformer" card that exercises the path.
Test plan
Verified on-device with the new example card (every keystroke throws):
RunTransformer→textInputDidChange). After: app stays alive, LogBox shows the error, input keeps the raw text.JSErrorcatch directly): typed 5 characters; app survived and the syslog shows five[rntti] Transformer threw an error: …entries with the value growing 1→5.