tl;dr: the D1 mini's usbserial interface is a little sketchy and macOS doesn't cope well. You need to install the driver from wch.cn. direct link to CH341SER_MAC.ZIP
SHA-512 sum (copy whole line, run pbpaste | shasum -c
in your download directory to check):
efb25faeb87d66a10e284629231fad7ebfbdbf2c2a50ed9b35f8dd9793398ff79df3da3312367dbc497dc62103195bc4eaf6399f8084f442bb1d1a7a51551eac *CH341SER_MAC.ZIP