LibJS: Convert to_bigint_int64() to ThrowCompletionOr

Author: https://github.com/IdanHo
Commit: df181809fd
Pull-request: https://github.com/SerenityOS/serenity/pull/10504
Reviewed-by: https://github.com/linusg

Userland/Libraries/LibJS/Runtime/Value.cpp

@@ -546,9 +546,9 @@ ThrowCompletionOr<BigInt*> Value::to_bigint(GlobalObject& global_object) const
 }
 
 // 7.1.15 ToBigInt64 ( argument ), https://tc39.es/ecma262/multipage/abstract-operations.html#sec-tobigint64
-i64 Value::to_bigint_int64(GlobalObject& global_object) const
+ThrowCompletionOr<i64> Value::to_bigint_int64(GlobalObject& global_object) const
 {
-    auto* bigint = TRY_OR_DISCARD(to_bigint(global_object));
+    auto* bigint = TRY(to_bigint(global_object));
     return static_cast<i64>(bigint->big_integer().to_u64());
 }