🐛 Fix fan index for Singlenozzle, chamber fan

Fixes #22512
Followup to #19152, #19519

Marlin/src/inc/SanityCheck.h

   #endif
 
   #if REDUNDANT_TEMP_MATCH(SOURCE, E0) && HAS_HOTEND
-    #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be 0 if a hotend is used. E0 always uses TEMP_SENSOR_0."
+    #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be E0 if a hotend is used. E0 always uses TEMP_SENSOR_0."
   #elif REDUNDANT_TEMP_MATCH(SOURCE, COOLER) && HAS_TEMP_COOLER
     #error "TEMP_SENSOR_REDUNDANT_SOURCE can't be COOLER. TEMP_SENSOR_COOLER is in use."
   #elif REDUNDANT_TEMP_MATCH(SOURCE, PROBE) && HAS_TEMP_PROBE

Marlin/src/module/temperature.cpp

       }
     #endif
 
-    TERN_(SINGLENOZZLE, fan = 0); // Always use fan index 0 with SINGLENOZZLE
+    TERN_(SINGLENOZZLE, if (fan < EXTRUDERS) fan = 0); // Always fan 0 for SINGLENOZZLE E fan
 
     if (fan >= FAN_COUNT) return;
 
             fan_chamber_pwm = CHAMBER_FAN_BASE + _MAX((CHAMBER_FAN_FACTOR) * (temp_chamber.celsius - temp_chamber.target), 0);
           #endif
           NOMORE(fan_chamber_pwm, 225);
-          set_fan_speed(2, fan_chamber_pwm); // TODO: instead of fan 2, set to chamber fan
+          set_fan_speed(CHAMBER_FAN_INDEX, fan_chamber_pwm); // TODO: instead of fan 2, set to chamber fan
         #endif
 
         #if ENABLED(CHAMBER_VENT)
       else if (!flag_chamber_off) {
         #if ENABLED(CHAMBER_FAN)
           flag_chamber_off = true;
-          set_fan_speed(2, 0);
+          set_fan_speed(CHAMBER_FAN_INDEX, 0);
         #endif
         #if ENABLED(CHAMBER_VENT)
           flag_chamber_excess_heat = false;