Catching CancellationException in coroutines

[LeafyLappa]

Description

I believe the implementation of error handling in coroutines could be improved by not catching all possible exceptions.

For example, in CharacterDetailViewModel there's this function:

    /**
     * Fetch selected character detail info.
     *
     * @param characterId Character identifier.
     */
    fun loadCharacterDetail(characterId: Long) {
        _state.postValue(CharacterDetailViewState.Loading)
        viewModelScope.launch {
            try {
                val result = marvelRepository.getCharacter(characterId)
                _data.postValue(characterDetailMapper.map(result))

                characterFavoriteRepository.getCharacterFavorite(characterId)?.let {
                    _state.postValue(CharacterDetailViewState.AlreadyAddedToFavorite)
                } ?: run {
                    _state.postValue(CharacterDetailViewState.AddToFavorite)
                }
            } catch (e: Exception) {
                _state.postValue(CharacterDetailViewState.Error)
            }
        }
    }

Here you could theoretically break the normal coroutine cancellation flow. If the coroutine here is cancelled for any reason then the app might show an error even when there's none.

By the way I've seen this kind of problem way too many times in actual production code. What's worse is that people won't even know how to properly fix it.

I generally use the solution I found here: https://betterprogramming.pub/the-silent-killer-thats-crashing-your-coroutines-9171d1e8f79b I find it very simple and nice as it could be used with runCatching...

[1145906886]

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