Error occurs when useEstimateGas or something that use bigint type in query key called.

[Hugo-Oh]

version

"wagmi": "^2.5.6",
"viem": "^2.7.6"

[TypeError: Do not know how to serialize a BigInt]

const populatedTx = {
    to: to,
    data: data,
    maxFeePerGas: parseEther('101', 'gwei'), //bigint
    maxPriorityFeePerGas: parseEther('100', 'gwei'), //bigint
    value: value,  //bigint
    chainId: targetChainId //number
  };
...
const estimatedGas = useEstimatedGas({...populatedGas, query: { gcTime: 1000*60*........}}
const unsignedTx = {populatedTx, gas: estimatedGas} 
...

So I modified my code like this

const populatedTx = {
    to: to,
    data: data,
    value: value,
    chainId: targetChainId 
  }; //remove any value that has any bigint type.
...
const estimatedGas = useEstimatedGas({...populatedGas, query: { gcTime....}};
const unsignedTx = {...populatedTx, 
gas: estimatedGas,  
maxFeePerGas: parseEther('101', 'gwei'),
maxPriorityFeePerGas: parseEther('100', 'gwei'), } 
...
...

useEstimateGas call uses UseEstimateGasParameters<Config, number, bigint> params as type, which can cause error as it contains bigint type.

I think whether disallowing bigint type, nor coverting bigint to number or string type is required.