I'm not sure whether that's really the cause of the error to be honest. I installed your CLI and tried to import the list of french postal codes from CSV file but I get an error on the first line. Here is my command:
DSIO_KEY_FILE=./service-account.json DSIO_PROJECT_ID=my-project-id dsio upsert ~/Downloads/insee.csv -k postalCodes
The CSV file is: https://raw.githubusercontent.com/Rudloff/french-postal-codes-api/master/insee.csv.
I'm on OSX 10.14.2. Here is the error message I get:

The CSV doesn't seem to be misformatted so I don't see what could be the problem.
Hope it helps to find if there is something to be fixed on your end.
I'm not sure whether that's really the cause of the error to be honest. I installed your CLI and tried to import the list of french postal codes from CSV file but I get an error on the first line. Here is my command:
DSIO_KEY_FILE=./service-account.json DSIO_PROJECT_ID=my-project-id dsio upsert ~/Downloads/insee.csv -k postalCodesThe CSV file is: https://raw.githubusercontent.com/Rudloff/french-postal-codes-api/master/insee.csv.
I'm on OSX 10.14.2. Here is the error message I get:

The CSV doesn't seem to be misformatted so I don't see what could be the problem.
Hope it helps to find if there is something to be fixed on your end.