Using SCL and SDA of ESP8266-01 with GY-30 BH1750FVI for lux measurement
Wire is not setup for the ESP01 by default. There is no GPIO 4 or 5. you can specify the pins as arguments to the begin() method, ex: Wire.begin(sda, scl). Using GPIO of (0,2) is common. Since the ESP01 is picky about pin states during power-up, don't use external pullups (you don't need them anyway).