A Redstone Lamp is powered by a redstone torch underneath it, If I now try to put redstone dust onto a block next to the redstone lamp it causes the redstone dust to blink before the lamp and the redstone torch cease to glow. In the moment the lamp turns off, you can hear the sound of lava.

This happened only in River biome, not in other biomes I tried. See attached video for a demonstration of the bug.