can't save code ESP32 with i2C oLED

I tried this and then saved using save().
However, LCD shows some dots but no text

function start(){
g.clear();
g.drawString("test",0,0);
g.flip();
}


E.on('init', function() { 
// I2C
I2C1.setup({scl:D4,sda:D5});
var g = require("SSD1306").connect(I2C1, start);
});