[REFACTOR]: [Klarna] Remove Default Case Handling

[Sakilmostak]

📝 Feature Description

• We utilize match statements to make pivotal decisions, such as generating requests based on the payment method type and managing responses received from the connector.
• These conditions generally go hand in hand with enum variants.
• Default case is used because a match statement needs to be exhaustive i.e. every variant needs to be covered.
• So, if all the explicit cases are handled then default is used to handle the rest.
• Each connector have these match statements but many of them don’t provide reference to each variant in their default case, rather a _ is put to handle all the other cases.
• This approach carries a risk because developers may inadvertently overlook the need for explicit handling of the new cases.

🔨 Possible Implementation

• Instead of relying on a default match case _, developers should handle each and every variant explicitly.
• By doing so, if there are any changes in the future, they can readily assess the impact of their modifications simply by compiling the code.
• You can check this PR for further reference refactor(connector): [Zen] refactor Zen payment methods not implemented errors #1955

🔖 Note: All the changes needed should be contained within hyperswitch/crates/router/src/connector/

📦 Have you spent some time checking if this feature request has been raised before?

• I checked and didn't find a similar issue

📦 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

✨ Are you willing to submit a PR?

[korrat]

I would like to work on this

[AkshayaFoiger]

Hey @korrat , sure! I've assigned this to you.

In case you have any queries, you can ask them on this issue thread, or on our discord server, or on slack whichever you are comfortable with