Skillshub flutter-error-handling

Functional error handling with Either/Failure. ALWAYS consult when writing repositories, handling exceptions, defining failures, or using Either in any Flutter layer — not just when setting up error handling. (triggers: lib/domain/**, lib/infrastructure/**, Either, fold, Left, Right, Failure, dartz)

install

source · Clone the upstream repo

git clone https://github.com/ComeOnOliver/skillshub

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/ComeOnOliver/skillshub "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/HoangNguyen0403/agent-skills-standard/flutter-error-handling" ~/.claude/skills/comeonoliver-skillshub-flutter-error-handling && rm -rf "$T"

manifest: skills/HoangNguyen0403/agent-skills-standard/flutter-error-handling/SKILL.md

source content

Error Handling

Priority: P1 (HIGH)

Standardized functional error handling using

dartz

and

freezed

failures.

Implementation Guidelines

Either Pattern: Return Either<Failure, T> from repositories. No exceptions in UI/BLoC.
Failures: Define domain-specific failures using @freezed unions (e.g.,
```
UnauthorizedFailure
```
,
```
OutOfStockFailure
```
).
Mapping: Infrastructure catches Exception (e.g.,
```
DioException
```
) and returns Left(Failure). Never rethrow to UI.
Consumption: Use .fold(failure, success) in BLoC to emit corresponding states. Remove try/catch from BLoC.
Typed Errors: Use
```
left(Failure())
```
and
```
right(Value())
```
from
```
Dartz
```
.
Low-Cardinality Logging: Use stable message templates; pass variable data via metadata/context.
Layer Restriction: try/catch only in Infrastructure. UI/Application/BLoC layers should not catch.
Localization: Use
```
failure.failureMessage
```
(returns TRObject or localized string) for UI-safe text.
Right/Left Restriction: Only Infrastructure may construct
```
Right()
```
/
```
Left()
```
.
No Silent Catch: Never swallow errors without logging or a documented retry.

Reference & Examples

For Failure definitions and API error mapping: See references/REFERENCE.md.

Anti-Patterns

❌
```
try { … } catch (e) { emit(ErrorState()); }
```
in BLoC — try/catch belongs only in Infrastructure; BLoC receives
```
Either
```
, then folds
❌
```
Left(Failure('Something went wrong'))
```
using a plain
```
String
```
— define typed
```
@freezed
```
Failure subclasses for each domain error
❌
```
catch (e) {}
```
empty catch — always log and propagate; never swallow silently
❌ Throwing
```
Exception
```
from a repository — return
```
Left(Failure)
```
instead; exceptions must not cross the infrastructure boundary