Improve conditions for HAS_TEMP

and use them in temperuture.h

Flattened the if structure - the preprocessor is doing the work - not the Arduino. Arduino.

Marlin/Conditionals.h

@@ -345,11 +345,11 @@
   /**
    * Shorthand for pin tests, for temperature.cpp
    */
-  #define HAS_TEMP_0 (defined(TEMP_0_PIN) && TEMP_0_PIN >= 0)
-  #define HAS_TEMP_1 (defined(TEMP_1_PIN) && TEMP_1_PIN >= 0)
-  #define HAS_TEMP_2 (defined(TEMP_2_PIN) && TEMP_2_PIN >= 0)
-  #define HAS_TEMP_3 (defined(TEMP_3_PIN) && TEMP_3_PIN >= 0)
-  #define HAS_TEMP_BED (defined(TEMP_BED_PIN) && TEMP_BED_PIN >= 0)
+  #define HAS_TEMP_0 (defined(TEMP_0_PIN) && TEMP_0_PIN >= 0 && TEMP_SENSOR_0 != 0 && TEMP_SENSOR_0 != -2)
+  #define HAS_TEMP_1 (defined(TEMP_1_PIN) && TEMP_1_PIN >= 0 && TEMP_SENSOR_1 != 0)
+  #define HAS_TEMP_2 (defined(TEMP_2_PIN) && TEMP_2_PIN >= 0 && TEMP_SENSOR_2 != 0)
+  #define HAS_TEMP_3 (defined(TEMP_3_PIN) && TEMP_3_PIN >= 0 && TEMP_SENSOR_3 != 0)
+  #define HAS_TEMP_BED (defined(TEMP_BED_PIN) && TEMP_BED_PIN >= 0 && TEMP_SENSOR_BED != 0)
   #define HAS_FILAMENT_SENSOR (defined(FILAMENT_SENSOR) && defined(FILWIDTH_PIN) && FILWIDTH_PIN >= 0)
   #define HAS_HEATER_0 (defined(HEATER_0_PIN) && HEATER_0_PIN >= 0)
   #define HAS_HEATER_1 (defined(HEATER_1_PIN) && HEATER_1_PIN >= 0)

Marlin/temperature.cpp

@@ -1543,7 +1543,7 @@ ISR(TIMER0_COMPB_vect) {
       if ((minttemp_raw[0]) GE0 (current_temperature_raw[0])) min_temp_error(0);
     #endif
 
-    #if EXTRUDERS > 1
+    #if HAS_TEMP_1
       #if HEATER_1_RAW_LO_TEMP > HEATER_1_RAW_HI_TEMP
         #define GE1 <=
       #else
@@ -1551,30 +1551,29 @@ ISR(TIMER0_COMPB_vect) {
       #endif
       if ((current_temperature_raw[1]) GE1 (maxttemp_raw[1])) max_temp_error(1);
       if ((minttemp_raw[1]) GE1 (current_temperature_raw[1])) min_temp_error(1);
+    #endif // TEMP_SENSOR_1
 
-      #if EXTRUDERS > 2
-        #if HEATER_2_RAW_LO_TEMP > HEATER_2_RAW_HI_TEMP
-          #define GE2 <=
-        #else
-          #define GE2 >=
-        #endif
-        if ((current_temperature_raw[2]) GE2 (maxttemp_raw[2])) max_temp_error(2);
-        if ((minttemp_raw[2]) GE2 (current_temperature_raw[2])) min_temp_error(2);
-
-        #if EXTRUDERS > 3
-          #if HEATER_3_RAW_LO_TEMP > HEATER_3_RAW_HI_TEMP
-            #define GE3 <=
-          #else
-            #define GE3 >=
-          #endif
-          if ((current_temperature_raw[3]) GE3 (maxttemp_raw[3])) max_temp_error(3);
-          if ((minttemp_raw[3]) GE3 (current_temperature_raw[3])) min_temp_error(3);
+    #if HAS_TEMP_2
+      #if HEATER_2_RAW_LO_TEMP > HEATER_2_RAW_HI_TEMP
+        #define GE2 <=
+      #else
+        #define GE2 >=
+      #endif
+      if ((current_temperature_raw[2]) GE2 (maxttemp_raw[2])) max_temp_error(2);
+      if ((minttemp_raw[2]) GE2 (current_temperature_raw[2])) min_temp_error(2);
+    #endif // TEMP_SENSOR_2
 
-        #endif // EXTRUDERS > 3
-      #endif // EXTRUDERS > 2
-    #endif // EXTRUDERS > 1
+    #if HAS_TEMP_3
+      #if HEATER_3_RAW_LO_TEMP > HEATER_3_RAW_HI_TEMP
+        #define GE3 <=
+      #else
+        #define GE3 >=
+      #endif
+      if ((current_temperature_raw[3]) GE3 (maxttemp_raw[3])) max_temp_error(3);
+      if ((minttemp_raw[3]) GE3 (current_temperature_raw[3])) min_temp_error(3);
+    #endif // TEMP_SENSOR_3
 
-    #if defined(BED_MAXTEMP) && (TEMP_SENSOR_BED != 0)
+    #if HAS_TEMP_BED
       #if HEATER_BED_RAW_LO_TEMP > HEATER_BED_RAW_HI_TEMP
         #define GEBED <=
       #else