Command failed: grunt server-build:prod --outputdir=courses/5ec4a2e80a55484546bab1b0/5ec8f1a3de3c825be173252f/build --theme=5ec4abac2b901d45cbe23969 --menu=adapt-contrib-boxMenu

Fatal error: {
"message": "variable @item-color-visited is undefined",
"type": "Name",
"filename": "src/components/adapt-blinds/less/blinds.less",
"index": 236,
"line": 18,
"column": 15,
"callLine": null,
"extract": [
"\t\t.blinds-item-overlay {",
"\t\t\tbackground: @item-color-visited;",
"\t\t\topacity: 0;"
]
}

Another error for another plug-in. It must be something simple. Or is is usually to have to tweek the plug-ins for oneself?