Implement reducers with handleActions

Currently most of our reducers are implemented as a big switch statement, which is unwieldy and hard to read. Instead, use the handleActions() helper in redux-actions to implement the reducer as a map of action names to reducer functions.

We should follow the pattern of using the action creator function itself as the map key, allowing us to avoid hard-coding string literals containing the action name.

See the console reducer for an example of the desired implementation.

Testing

Since our goal here is merely to refactor the reducers, not change their behavior, all existing tests should pass after a reducer is refactored.

However, it might make sense to also port the reducer test to Jest after completing the refactor and confirming that the old tests pass with the new reducer implementation (this should be in separate commits).

Reducers to migrate

• clients
• compiledProjects
• console
• currentProject
• errors
• googleClassroom
• index
• projects
• resizableFlex
• ui
• user

Comienza con el ejemplo completado en src/reducers/console.js; después, localiza los reducers aún no comprobados clients, compiledProjects, currentProject, errors, googleClassroom, index, projects y user. Refactorízalos con redux-actions preservando el comportamiento y ejecuta todas las pruebas existentes para confirmar que siguen pasando; deja la migración de las pruebas de Jest para un cambio separado.