Minerbot made in Minecraft MakeCode - Javascript code. Still need to figure out what to do, if the block you're destroying is sand or gravel, as it falls down.

Minerbot

function GoHomeWithLoot () {
    LastMiningPosition = agent.getPosition()
    agent.teleport(Home, WEST)
    agent.dropAll(DOWN)
    agent.teleport(LastMiningPosition, WEST)
    player.say("start mining")
}
function CheckForGravel () {
    while (blocks.testForBlock(GRASS, positions.add(
    agent.getPosition(),
    pos(0, 0, -1)
    ))) {
        agent.destroy(FORWARD)
        CheckForGravel()
    }
}
player.onChat("start mining", function (num1) {
    while (true) {
        for (let index = 0; index < 100; index++) {
            WalkAndAvoidLava()
        }
        GoHomeWithLoot()
    }
})
player.onChat("back", function () {
    player.teleport(lastPlayerPosition)
    mobs.clearEffect(mobs.target(LOCAL_PLAYER))
})
function MakeStaircase () {
    for (let index = 0; index < 1; index++) {
        if (agent.detect(AgentDetection.Block, FORWARD)) {
            while (agent.detect(AgentDetection.Block, FORWARD)) {
                agent.destroy(FORWARD)
            }
        }
        if (agent.detect(AgentDetection.Block, DOWN)) {
            agent.destroy(DOWN)
        }
        agent.move(DOWN, 1)
        agent.move(FORWARD, 1)
    }
}
function MakeTunnel () {
    CheckForGravel()
    if (agent.detect(AgentDetection.Block, FORWARD)) {
        agent.destroy(FORWARD)
    }
    TestForLavaAndRemoveIfFound()
    if (agent.detect(AgentDetection.Block, LEFT)) {
        agent.destroy(LEFT)
    }
    TestForLavaAndRemoveIfFound()
    agent.move(LEFT, 1)
    if (agent.detect(AgentDetection.Block, UP)) {
        agent.destroy(UP)
    }
    TestForLavaAndRemoveIfFound()
    agent.move(UP, 1)
    if (agent.detect(AgentDetection.Block, RIGHT)) {
        agent.destroy(RIGHT)
    }
    TestForLavaAndRemoveIfFound()
    agent.move(RIGHT, 1)
    agent.move(DOWN, 1)
    agent.move(FORWARD, 1)
}
/**
 * Makes a 2 wide and 2 tall tunnel and moves 1 forward
 */
function TestForLavaAndRemoveIfFound () {
    if (blocks.testForBlock(LAVA, positions.add(
    agent.getPosition(),
    pos(0, -1, -1)
    ))) {
        player.say("my Agent found lava!")
        agent.setItem(WATER, 1, 1)
        blocks.place(WATER, positions.add(
        agent.getPosition(),
        pos(0, 0, -1)
        ))
        loops.pause(500)
        blocks.place(AIR, positions.add(
        agent.getPosition(),
        pos(0, 0, -1)
        ))
    }
}
player.onChat("tptome", function () {
    agent.teleportToPlayer()
})
player.onChat("gohome", function () {
    GoHomeWithLoot()
})
function CollectResources () {
    agent.collectAll()
}
player.onChat("stop mining", function () {
    player.tell(mobs.target(LOCAL_PLAYER), "I'll wait")
})
player.onChat("tominer", function () {
    lastPlayerPosition = player.position()
    player.teleport(agent.getPosition())
    mobs.applyEffect(NIGHT_VISION, mobs.target(LOCAL_PLAYER), 600, 255)
})
function WalkAndAvoidLava () {
    TestForLavaAndRemoveIfFound()
    MinerLogic()
}
function MinerLogic () {
    if (agent.getPosition().getValue(Axis.Y) == 12) {
        MakeTunnel()
        CollectResources()
    } else {
        MakeStaircase()
    }
}
player.onChat("home", function () {
    Home = player.position()
})
let lastPlayerPosition: Position = null
let Home: Position = null
let LastMiningPosition: Position = null
LastMiningPosition = agent.getPosition()
agent.teleport(LastMiningPosition, NORTH)