Use size constants for MAPSEC popup theme array

src/map_name_popup.c

@@ -69,7 +69,10 @@ static const u16 sMapPopUp_PaletteTable[][16] =
 
 static const u16 sMapPopUp_Palette_Underwater[16] = INCBIN_U16("graphics/map_popup/underwater.gbapal");
 
-static const u8 sRegionMapSectionId_To_PopUpThemeIdMapping[] =
+// -1 in the size excludes MAPSEC_NONE.
+// The MAPSEC values for Kanto (between MAPSEC_DYNAMIC and MAPSEC_AQUA_HIDEOUT) are also excluded,
+// and this is then handled by subtracting KANTO_MAPSEC_COUNT here and in LoadMapNamePopUpWindowBg.
+static const u8 sMapSectionToThemeId[MAPSEC_COUNT - KANTO_MAPSEC_COUNT - 1] =
 {
     [MAPSEC_LITTLEROOT_TOWN] = MAPPOPUP_THEME_WOOD,
     [MAPSEC_OLDALE_TOWN] = MAPPOPUP_THEME_WOOD,
@@ -174,7 +177,7 @@ static const u8 sRegionMapSectionId_To_PopUpThemeIdMapping[] =
     [MAPSEC_DESERT_UNDERPASS - KANTO_MAPSEC_COUNT] = MAPPOPUP_THEME_STONE,
     [MAPSEC_ALTERING_CAVE - KANTO_MAPSEC_COUNT] = MAPPOPUP_THEME_STONE,
     [MAPSEC_NAVEL_ROCK - KANTO_MAPSEC_COUNT] = MAPPOPUP_THEME_STONE,
-    [MAPSEC_TRAINER_HILL - KANTO_MAPSEC_COUNT] = MAPPOPUP_THEME_MARBLE
+    [MAPSEC_TRAINER_HILL - KANTO_MAPSEC_COUNT] = MAPPOPUP_THEME_MARBLE,
 };
 
 static const u8 sText_PyramidFloor1[] = _("PYRAMID FLOOR 1");
@@ -410,7 +413,7 @@ static void LoadMapNamePopUpWindowBg(void)
         else
             regionMapSectionId = 0; // Discard kanto region sections;
     }
-    popUpThemeId = sRegionMapSectionId_To_PopUpThemeIdMapping[regionMapSectionId];
+    popUpThemeId = sMapSectionToThemeId[regionMapSectionId];
 
     LoadBgTiles(GetWindowAttribute(popupWindowId, WINDOW_BG), sMapPopUp_OutlineTable[popUpThemeId], 0x400, 0x21D);
     CallWindowFunction(popupWindowId, DrawMapNamePopUpFrame);