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fix(mix): report FlutterErrorDetails in debug mode when Prop value conversion fails #1096

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Merged
leoafarias merged 5 commits into from
Oct 21, 2026
Merged

fix(mix): report FlutterErrorDetails in debug mode when Prop value conversion fails #1096

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ef1c9a3
fix(mix): throw FlutterError in debug mode when Prop value conversion…
leoafarias Oct 15, 2026
a9c8f1a
fix(mix): use FlutterError.reportError so resolveProp returns fallbac…
leoafarias Oct 15, 2026
328b63d
fix(mix): preserve latest source fallback order when Mix conversion f…
leoafarias Oct 15, 2026
b767c8c
Merge remote-tracking branch 'origin/main' into HEAD
leoafarias Oct 21, 2026
67c5569
fix(mix): document the Prop fallback change and split its test
leoafarias Oct 21, 2026
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15 changes: 11 additions & 4 deletions packages/mix/lib/src/core/prop.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -242,11 +242,18 @@ class Prop<V> {
if (converted != null) {
mixValues.add(converted);
} else {
// Debug-only diagnostic to surface silent conversion failures
// Debug-only diagnostic to surface silent conversion failures while
// still returning the fallback resolved value.
assert(() {
debugPrint(
'Mix: could not convert value of type ${value.runtimeType} '
'to Mix<$V>. Register a MixConverter for <$V> or pass a Mix via Prop.mix.',
FlutterError.reportError(

@chatgpt-codex-connector chatgpt-codex-connector Bot Oct 15, 2026

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P2 Badge Throw instead of only reporting conversion failures

When a converter is missing in a debug build, FlutterError.reportError invokes the global FlutterError.onError handler and then returns; it does not throw. Consequently, resolveProp still drops the unconverted value and returns the remaining Mix result, and a handler can swallow the error exactly as this new test does, so the intended fail-fast behavior is not implemented. Throw the FlutterError from the assertion block and test with throwsA if resolution is meant to abort.

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@leoafarias leoafarias Oct 21, 2026

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Intentional: the first commit threw, and a9c8f1a switched to FlutterError.reportError so a missing converter is reported, like other recoverable framework errors (layout overflow), while the widget still renders the latest source. Reported errors reach FlutterError.onError, which fails widget tests. The CHANGELOG entry now records this and the release-mode fallback change.

FlutterErrorDetails(
exception: FlutterError(
'Mix: could not convert value of type ${value.runtimeType} '
'to Mix<$V>. Register a MixConverter for <$V> or pass a Mix via Prop.mix.',
),
library: 'mix',
context: ErrorDescription('while resolving Prop<$V>'),
),
);

return true;
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27 changes: 27 additions & 0 deletions packages/mix/test/src/core/prop_test.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -191,5 +191,32 @@ void main() {
expect(resolved.right, 8.0); // from converted prop1
expect(resolved.bottom, 8.0); // from converted prop1
});

test(
'reports FlutterErrorDetails in debug mode and returns fallback value when merging an unconverted value with a Mix',
() {
final prop1 = Prop.value(10.0);
final prop2 = Prop.mix(MockMix<double>(20.0));
final merged = prop1.mergeProp(prop2);

FlutterErrorDetails? reported;
final previousOnError = FlutterError.onError;
FlutterError.onError = (details) {
reported = details;
};
addTearDown(() => FlutterError.onError = previousOnError);

final resolved = merged.resolveProp(MockBuildContext());

expect(resolved, 20.0);
expect(reported, isNotNull);
expect(
reported!.exceptionAsString(),
contains(
'Mix: could not convert value of type double to Mix<double>',
),
);
},
);
});
}
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