Account Modal Bugfix (#3687)

## Description:

Fix null stat values from LEFT JOIN causing Zod validation failure on
player profiles

https://github.com/openfrontio/infra/pull/316 switched playerStats from
innerJoin to leftJoin so that sessions with no stats row (games that
ended instantly on spawn) are still counted in wins/losses/total.


## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

w.o.n

src/core/StatsSchemas.ts

@@ -94,6 +94,7 @@ export const OTHER_INDEX_LOST = 3; // Structures/warships destroyed/captured by
 export const OTHER_INDEX_UPGRADE = 4; // Structures upgraded
 
 export const BigIntStringSchema = z.preprocess((val) => {
+  if (val === null) return 0n;
   if (typeof val === "string" && /^-?\d+$/.test(val)) return BigInt(val);
   if (typeof val === "bigint") return val;
   return val;