Calling balance_of via smart contract gives error A FAILWITH instruction was reached with 19

Question

I am trying to call "balance_of" entrypoint of fxhash contract (in ghostnet).

Deployed contract: https://better-call.dev/ghostnet/KT1FqmrtKA4Pz4cNDsikt8qrwEg8pdSCpYug/interact/check

I used "tz1QeSqtvZkW8drygD3h6oaEqPKq6Lhu4UKF" & "1031" because these parameters were used in previous successful balance_of call.

here is code:

@sp.entry_point
def ballance(self, params):
    sp.for x in params:
        self.data.exist = x.balance

@sp.entry_point
def check(self):
    c = sp.contract(
            sp.TRecord(
                requests= 
                    sp.TList(
                        sp.TRecord(
                        owner=sp.TAddress,
                        token_id=sp.TNat,
                        )
                    ), 
                callback = sp.TContract(
                        sp.TList(
                            sp.TRecord(
                                request = sp.TRecord(
                                    owner=sp.TAddress,
                                    token_id=sp.TNat,
                                ),
                                balance=sp.TNat
                            )
                        )
                    )
            )
        , 
        sp.address("KT1NkZho1yRkDdQnN4Mz93sDYyY2pPrEHTNs"), 
        entry_point = "balance_of").open_some()

    requests =  sp.list([sp.record(owner = sp.address("tz1QeSqtvZkW8drygD3h6oaEqPKq6Lhu4UKF"),token_id = 1031)])
    params = sp.record(callback = sp.self_entry_point(entry_point ="ballance"), requests = requests)    
    sp.transfer(params, sp.mutez(0), c)

"ballance" entrypoint working fine when I make a direct call to it manually.

when I make call to "check" entrypoint fails,

in simulation,

A FAILWITH instruction was reached with 19

with temple wallet call,

[ { "kind": "temporary", "id": "proto.013-PtJakart.michelson_v1.runtime_error", "contract_handle": "KT1FqmrtKA4Pz4cNDsikt8qrwEg8pdSCpYug" }, { "kind": "temporary", "id": "proto.013-PtJakart.michelson_v1.script_rejected", "location": 53, "with": { "int": "19" } } ]

Answer 1

The error comes from line 19 entry_point = "balance_of").open_some(), .open_some() is including the source line when sp.contract(...) resolves to None.

The error seems be caused by having the wrong layouts.

This should fix the issue:

         c = sp.contract(
            sp.TRecord(
                requests= 
                    sp.TList(
                        sp.TRecord(
                           owner=sp.TAddress, 
                           token_id=sp.TNat
                        ).layout(("owner", "token_id"))
                    ), 
                callback = sp.TContract(
                        sp.TList(
                            sp.TRecord(
                                request = sp.TRecord(
                                    owner=sp.TAddress, 
                                    token_id=sp.TNat
                                ).layout(("owner", "token_id")),
                                balance=sp.TNat
                            ).layout(("request", "balance"))
                        )
                    )
            ).layout(("requests", "callback"))
        , 
        sp.address("KT1NkZho1yRkDdQnN4Mz93sDYyY2pPrEHTNs"), 
        entry_point = "balance_of").open_some()