`setUserSession` and `replaceUserSession` Lack Error Handling for Session Storage Failures

[CorrM]

The setUserSession and replaceUserSession methods return a UserSession object that reflects the intended session data, even when the data fails to persist due to storage limits 4096-byte.
This behavior creates a false assumption that the data was saved successfully.

For example:

const newSession = { user: { id: 1 }, token: "large-token-data" };
const result = await setUserSession(event, newSession);
console.log(result); // Outputs `newSession`, even if it wasn't saved

const currentSession = await getUserSession(event);
console.log(currentSession ); // Outputs outdated data

Expected Behavior

If session persistence fails, the methods should throw an error or return a status indicating failure.
The returned UserSession object should only reflect successfully persisted data.

[atinux]

Indeed, it might be tricky as the data is encoded to know when to throw an error :(