[neopixelbus] Fix ESP8266 compilation by enabling Serial/Serial1 for NeoPixelBus library (#13027)

esphome/components/neopixelbus/light.py

@@ -194,6 +194,14 @@ CONFIG_SCHEMA = cv.All(
 
 
 async def to_code(config):
+    if CORE.is_esp8266:
+        # NeoPixelBus library unconditionally includes NeoEsp8266UartMethod.h
+        # which references Serial and Serial1, so we must enable both
+        from esphome.components.esp8266.const import enable_serial, enable_serial1
+
+        enable_serial()
+        enable_serial1()
+
     has_white = "W" in config[CONF_TYPE]
     method = config[CONF_METHOD]