Add more assert cases in the codebase (#1115)

* Add assert for FACING_GRASS_1 and FACING_GRASS_2

* Add more assert cases

* Add assert for HP bar colors

* Assert LINK_NULL == 0

* Fix assert syntax

* Add asserts for WILD_BATTLE == 1

* Add additional WILD assert

- I need to sleep more...

* Revert asserts for WILD_BATTLE and LINK_NULL

* Commit suggested changes

* Add more assert cases

* Fix syntax error

engine/items/pack.asm

@@ -501,11 +501,14 @@ TossMenu:
 
 ResetPocketCursorPositions: ; unreferenced
 	ld a, [wCurPocket]
-	and a ; ITEM_POCKET
+	assert ITEM_POCKET == 0
+	and a
 	jr z, .items
-	dec a ; BALL_POCKET
+	assert BALL_POCKET == 1
+	dec a
 	jr z, .balls
-	dec a ; KEY_ITEM_POCKET
+	assert KEY_ITEM_POCKET == 2
+	dec a
 	jr z, .key
 	ret