sending a transaction requires a signer

I have an NFT Contract and i need to mint nft also i have a second contract
for handle buy and sell nft into this contract .

i using the ethers library .

this is my code for config :

static async Initial(): Promise<any> {

    let provider = new ethers.providers.JsonRpcProvider(config.contractConfig.url);
    const signer = provider.getSigner();
    
    this.tokenContract = new ethers.Contract(config.contractConfig.nftAddress, NFT.abi, provider);
    this.dNFT = new ethers.Contract(config.contractConfig.dortajNftAddress, DNFT.abi, signer);

}

config address :

  export default {
     nftAddress: '0x444F15B115ED9663DAE46786a34AA3F6E8c0B57D',
     dortajNftAddress: '0x8e4bE2a3BD1169596c38952D8e837b20D419Bcd1',
     url : 'HTTP://127.0.0.1:7545'
   }

now i need to use this function for mint nft :

        let transaction = await this.tokenContract.mintToken();
        const tx = await transaction.wait();

but it show me this error ;

Error: sending a transaction requires a signer (operation="sendTransaction", code=UNSUPPORTED_OPERATION, version=contracts/5.5.0)

how can i solve this problem ?

>Solution :

In this line

this.tokenContract = new ethers.Contract(config.contractConfig.nftAddress, NFT.abi, provider);

try to pass signer instead of provider.