fix(IT Wallet): [SIW-695] Fix credentials issuing checks error naviga…

…tion (#5237)

## Short description
This PR proposes a fix for the credential catalog screen not navigating
to the checks result screen on error.
The issue comes from the condition on the navigation `pot.isNone` which
evaluates to true when the pot is in `NoneError` state, thus preventing
the navigation to the result screen.

## List of changes proposed in this pull request
- Removes the `pot.isNone` condition leaving only `pot.isLoading`. This
is sufficient because we only want to navigate when the pot is not in a
loading state and the loading index is not `-1`.
If the pot is `none`, when the user opens the catalog, the condition
will still fail due to the loading index being none.
If the pot is `noneError` after the user selects a credential, then the
navigation happens due to the loading index being different from none.
However, if the pot is `noneError` because an error occurred and the
user lands again in the credential catalog, the navigation won't happen
because the loading index is being none.

## How to test
Check if obtaining a credential still works properly and also check if
the "already existing credential" error is shown.

ts/features/it-wallet/screens/credential/issuing/ItwCredentialsCatalogScreen.tsx

@@ -51,13 +51,9 @@ const ItwCredentialCatalogScreen = () => {
    * when the user goes back from the credential checks screen.
    */
   useEffect(() => {
-    if (
-      loadingIndex !== NONE_LOADING &&
-      !pot.isLoading(preliminaryChecks) &&
-      !pot.isNone(preliminaryChecks)
-    ) {
-      setLoadingIndex(-1);
+    if (loadingIndex !== NONE_LOADING && !pot.isLoading(preliminaryChecks)) {
       navigation.navigate(ITW_ROUTES.CREDENTIAL.ISSUING.CHECKS);
+      setLoadingIndex(NONE_LOADING);
     }
   }, [loadingIndex, navigation, preliminaryChecks]);