fix: init account balance if account is not exist

Author: roxie-23

Makefile

@@ -48,11 +48,11 @@ linter:
 
 
 contract-zip:
-	@mkdir tmp && cd tmp && unzip ../example/contracts.zip
+	@rm -rf tmp && mkdir tmp && cd tmp && unzip -q ../example/contracts.zip
 	@cd example/contracts/src/broker && cp -r ../../../../tmp/contracts/src/broker/vendor ./
 	@cd example/contracts/src/data_swapper && cp -r ../../../../tmp/contracts/src/data_swapper/vendor ./
 	@cd example/contracts/src/transfer && cp -r ../../../../tmp/contracts/src/transfer/vendor ./
 	@cd example/contracts/src/transaction && cp -r ../../../../tmp/contracts/src/transaction/vendor ./
 	@rm -rf tmp example/contracts.zip
-	@cd example && zip -r contracts.zip contracts
+	@cd example && zip -r -q contracts.zip contracts
 	@printf "${GREEN}Build contracts.zip successfully!${NC}\n"

example/contracts.zip

@@ -21,7 +21,10 @@ func getUint64(stub shim.ChaincodeStubInterface, key string) (uint64, error) {
 	if err != nil {
 		return 0, fmt.Errorf("amount must be an interger %w", err)
 	}
-
+	// init value if not exist
+	if value == nil {
+		return 0, nil
+	}
 	ret, err := strconv.ParseUint(string(value), 10, 64)
 	if err != nil {
 		return 0, err