Pins should always be defined (even for disabled features)

Marlin/pins_A4JP.h

   #endif
 #endif // VIKI2/miniVIKI
 
-#if ENABLED(FILAMENT_SENSOR)
-  //Filip added pin for Filament sensor analog input
-  #define FILWIDTH_PIN        3
-#endif
+#define FILWIDTH_PIN        3  // ANALOG NUMBERING
 
 /************************************************
  * Rambo pin assignments old

Marlin/pins_PRINTRBOARD.h

 #define TEMP_0_PIN          1  // Extruder / Analog pin numbering
 #define TEMP_BED_PIN        0  // Bed / Analog pin numbering
 
-#if ENABLED(FILAMENT_SENSOR)
-  #define FILWIDTH_PIN      2
-#endif
+#define FILWIDTH_PIN        2  // ANALOG NUMBERING
 
 #define TEMP_1_PIN         -1
 #define TEMP_2_PIN         -1

Marlin/pins_PRINTRBOARD_REVF.h

 #define TEMP_0_PIN          1  // Extruder / Analog pin numbering
 #define TEMP_BED_PIN        0  // Bed / Analog pin numbering
 
-#if ENABLED(FILAMENT_SENSOR)
-  #define FILWIDTH_PIN      2
-#endif
+#define FILWIDTH_PIN        2  // ANALOG NUMBERING
 
 #define TEMP_1_PIN         -1
 #define TEMP_2_PIN         -1

Marlin/pins_RAMBO.h

 #define LED_PIN            13
 #define FAN_PIN            8
 
+#define FILWIDTH_PIN        3  // ANALOG NUMBERING
+
 /**********************************************************
   Fan Pins
   Fan_0 8
   #endif
 #endif // VIKI2/miniVIKI
 
-#if ENABLED(FILAMENT_SENSOR)
-  //Filip added pin for Filament sensor analog input
-  #define FILWIDTH_PIN        3
-#endif

Marlin/pins_RAMPS_14.h

 #define SDSS               53
 #define LED_PIN            13
 
-#if ENABLED(FILAMENT_SENSOR)  // FMM added for Filament Extruder
-  // define analog pin for the filament width sensor input
-  // Use the RAMPS 1.4 Analog input 5 on the AUX2 connector
-  #define FILWIDTH_PIN      5
-#endif
+// Use the RAMPS 1.4 Analog input 5 on the AUX2 connector
+#define FILWIDTH_PIN        5 // ANALOG NUMBERING
 
 #if ENABLED(Z_MIN_PROBE_ENDSTOP)
   // Define a pin to use as the signal pin on Arduino for the Z_PROBE endstop.