🎨 Better error message for bad array sizes

Marlin/src/inc/SanityCheck.h

@@ -2804,23 +2804,30 @@ constexpr float sanity_arr_1[] = DEFAULT_AXIS_STEPS_PER_UNIT,
                 sanity_arr_3[] = DEFAULT_MAX_ACCELERATION;
 
 #define _ARR_TEST(N,I) (sanity_arr_##N[_MIN(I,int(COUNT(sanity_arr_##N))-1)] > 0)
+#if HAS_MULTI_EXTRUDER
+  #define _EXTRA_NOTE " (Did you forget to enable DISTINCT_E_FACTORS?)"
+#elif EXTRUDERS == 0
+  #define _EXTRA_NOTE " (Note: EXTRUDERS is set to 0.)"
+#else
+  #define _EXTRA_NOTE ""
+#endif
 
 static_assert(COUNT(sanity_arr_1) >= XYZE,   "DEFAULT_AXIS_STEPS_PER_UNIT requires X, Y, Z and E elements.");
-static_assert(COUNT(sanity_arr_1) <= XYZE_N, "DEFAULT_AXIS_STEPS_PER_UNIT has too many elements. (Did you forget to enable DISTINCT_E_FACTORS?)");
+static_assert(COUNT(sanity_arr_1) <= XYZE_N, "DEFAULT_AXIS_STEPS_PER_UNIT has too many elements." _EXTRA_NOTE);
 static_assert(   _ARR_TEST(1,0) && _ARR_TEST(1,1) && _ARR_TEST(1,2)
               && _ARR_TEST(1,3) && _ARR_TEST(1,4) && _ARR_TEST(1,5)
               && _ARR_TEST(1,6) && _ARR_TEST(1,7) && _ARR_TEST(1,8),
               "DEFAULT_AXIS_STEPS_PER_UNIT values must be positive.");
 
 static_assert(COUNT(sanity_arr_2) >= XYZE,   "DEFAULT_MAX_FEEDRATE requires X, Y, Z and E elements.");
-static_assert(COUNT(sanity_arr_2) <= XYZE_N, "DEFAULT_MAX_FEEDRATE has too many elements. (Did you forget to enable DISTINCT_E_FACTORS?)");
+static_assert(COUNT(sanity_arr_2) <= XYZE_N, "DEFAULT_MAX_FEEDRATE has too many elements." _EXTRA_NOTE);
 static_assert(   _ARR_TEST(2,0) && _ARR_TEST(2,1) && _ARR_TEST(2,2)
               && _ARR_TEST(2,3) && _ARR_TEST(2,4) && _ARR_TEST(2,5)
               && _ARR_TEST(2,6) && _ARR_TEST(2,7) && _ARR_TEST(2,8),
               "DEFAULT_MAX_FEEDRATE values must be positive.");
 
 static_assert(COUNT(sanity_arr_3) >= XYZE,   "DEFAULT_MAX_ACCELERATION requires X, Y, Z and E elements.");
-static_assert(COUNT(sanity_arr_3) <= XYZE_N, "DEFAULT_MAX_ACCELERATION has too many elements. (Did you forget to enable DISTINCT_E_FACTORS?)");
+static_assert(COUNT(sanity_arr_3) <= XYZE_N, "DEFAULT_MAX_ACCELERATION has too many elements." _EXTRA_NOTE);
 static_assert(   _ARR_TEST(3,0) && _ARR_TEST(3,1) && _ARR_TEST(3,2)
               && _ARR_TEST(3,3) && _ARR_TEST(3,4) && _ARR_TEST(3,5)
               && _ARR_TEST(3,6) && _ARR_TEST(3,7) && _ARR_TEST(3,8),
@@ -2863,6 +2870,7 @@ static_assert(   _ARR_TEST(3,0) && _ARR_TEST(3,1) && _ARR_TEST(3,2)
 #endif
 
 #undef _ARR_TEST
+#undef _EXTRA_NOTE
 
 #if BOTH(CNC_COORDINATE_SYSTEMS, NO_WORKSPACE_OFFSETS)
   #error "CNC_COORDINATE_SYSTEMS is incompatible with NO_WORKSPACE_OFFSETS."