Check that AMPEL_WIFI is defined and not empty

ampel-firmware/ampel-firmware.h

@@ -13,7 +13,7 @@
 
 #include "wifi_util.h"
 #include "mqtt.h"
-#ifdef AMPEL_HTTP
+#if (AMPEL_HTTP==1) //TODO: Is it still needed?
 #  include "web_server.h"
 #endif
 

ampel-firmware/ampel-firmware.ino

@@ -122,7 +122,7 @@ void setup() {
 
   if (config::wifi_active) {
     wifi::defineCommands();
-#  ifdef AMPEL_HTTP
+#  if (AMPEL_HTTP==1)
     web_server::definePages();
     //TODO: Rename. Not just web_server
     // web_server::initialize();

ampel-firmware/web_config.cpp

@@ -11,6 +11,11 @@
 #  error Missing config.h file. Please copy config.public.h to config.h.
 #endif
 
+// Make sure AMPEL_WIFI is defined and not empty:
+#if !defined(AMPEL_WIFI) || (7-AMPEL_WIFI-7 == 14)
+#  error config.h has a new structure, please update it from config.public.h (e.g. AMPEL_WIFI should be set to true or false)
+#endif
+
 #include "util.h"
 #include "sensor_console.h"