By adding “setuptex” in the task file, it runs well and makes a pdf output.

	{
            "label": "ConTeXt Compile",
            "type": "shell",
            "command": "source ~/ConTeXtLMTX/tex/setuptex;context '${file}'",
            "args": [],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        },

Thank you.
Best regards,

Dalyoung