dbAuth: Catch fetch failure in getToken (#9119)

We have this comment in `useToken()`


https://github.com/redwoodjs/redwood/blob/4b734d30c6830172194a2518ae0c2cbf6f1a0904/packages/auth/src/AuthProvider/useToken.ts#L7-L14

And for example our Netlify auth implementation does this:


https://github.com/redwoodjs/redwood/blob/4b734d30c6830172194a2518ae0c2cbf6f1a0904/packages/auth-providers/netlify/web/src/netlify.ts#L68-L78

But dbAuth let the exception slip through to `useToken`.
This PR adds a `catch` to the promise and returns `null`, just like
Netlify (and others)


Before merging this though, I need to make sure I'm not undoing the fix
@standup75 did in #8284
(@standup75 can you say off the top of your head if my code will work or
not?)

packages/auth-providers/dbAuth/web/src/dbAuth.ts

@@ -96,6 +96,9 @@ export function createDbAuthClient({
           cachedToken = tokenText.length === 0 ? null : tokenText
           return cachedToken
         })
+        .catch(() => {
+          return null
+        })
         .finally(() => {
           getTokenPromise = null
         })