Fixed crash when slot is invalid in potion command

Now, instead of a crash because of an unhandled
IndexOutOfBoundsException, the command will return and print the reason
it failed and the valid slots to use to the DevConsole

src/main/java/basemod/DevConsole.java

@@ -946,6 +946,12 @@ private static void cmdPotion(String[] tokens) {
 			log("use potion list to see valid ids");
 			return;
 		}
+
+		if (AbstractDungeon.player != null && (i >= AbstractDungeon.player.potionSlots || i < 0)) {
+			log("cannot obtain potion in invalid slot " + i);
+			log("use values between 0 and " + (AbstractDungeon.player.potionSlots - 1));
+			return;
+		}
 
 		AbstractDungeon.player.obtainPotion(i, p);
 	}