Don't attempt to use adjusted EXP counter in invalid contexts

- Introduces new function K_GetDisplayEXP
    - Replaces duplicated code between HUD and tally
    - Returns UINT16_MAX in div/0 case for invalid result (resolves #1458)
- Hides EXP HUD/tally if no EXP can be earned

src/k_hud.cpp

@@ -3116,17 +3116,19 @@ static void K_drawKartTeamScores(void)
 	}
 }
 
-static void K_drawKartLaps(void)
+static boolean K_drawKartLaps(void)
 {
 	INT32 splitflags = V_SNAPTOBOTTOM|V_SNAPTOLEFT|V_SPLITSCREEN;
 	INT32 bump = 0;
 	boolean drewsticker = false;
 
+	UINT16 displayEXP = K_GetDisplayEXP(stplyr);
+
 	// Jesus Christ.
 	// I do not understand the way this system of offsets is laid out at all,
 	// so it's probably going to be pretty bad to maintain. Sorry.
 
-	if (numlaps != 1)
+	if (numlaps != 1 && displayEXP != UINT16_MAX)
 	{
 		if (r_splitscreen > 1)
 			bump = 27;
@@ -3196,10 +3198,12 @@ static void K_drawKartLaps(void)
 		}
 	}
 
-	UINT16 displayEXP = std::clamp(FixedMul(std::max(stplyr->exp, FRACUNIT/2), (500/K_GetNumGradingPoints())*stplyr->gradingpointnum), 0, 999);
-
 	// EXP
-	if (r_splitscreen > 1)
+	if (displayEXP == UINT16_MAX)
+	{
+		;
+	}
+	else if (r_splitscreen > 1)
 	{
 		INT32 fx = 0, fy = 0, fr = 0;
 		INT32 flipflag = 0;
@@ -3263,6 +3267,8 @@ static void K_drawKartLaps(void)
 		Draw row = Draw(LAPS_X+23+bump, LAPS_Y+3).flags(V_HUDTRANS|V_SLIDEIN|splitflags).font(Draw::Font::kThinTimer);
 		row.text("{:03}", displayEXP);
 	}
+
+	return drewsticker;
 }
 
 #define RINGANIM_FLIPFRAME (RINGANIM_NUMFRAMES/2)
@@ -6823,8 +6829,7 @@ void K_drawKartHUD(void)
 			{
 				if (gametyperules & GTR_CIRCUIT)
 				{
-					K_drawKartLaps();
-					gametypeinfoshown = true;
+					gametypeinfoshown = K_drawKartLaps();
 				}
 				else if (gametyperules & GTR_BUMPERS)
 				{

src/k_kart.c

@@ -15237,6 +15237,29 @@ fixed_t K_GetExpAdjustment(player_t *player)
 	return result;
 }
 
+UINT16 K_GetDisplayEXP(player_t *player)
+{
+	UINT32 numgradingpoints = K_GetNumGradingPoints();
+
+	if (!numgradingpoints)
+		return UINT16_MAX;
+
+	fixed_t result = max(player->exp, FRACUNIT/2);
+	result = FixedMul(result, (500/numgradingpoints)*player->gradingpointnum);
+
+	// bro where is. bro where is std::clamp
+	if (result < 0)
+	{
+		result = 0;
+	}
+	else if (result > 999)
+	{
+		result = 999;
+	}
+
+	return result;
+}
+
 UINT32 K_GetNumGradingPoints(void)
 {
 	return numlaps * (1 + Obj_GetCheckpointCount());

src/k_kart.h

@@ -298,6 +298,8 @@ boolean K_PlayerCanUseItem(player_t *player);
 
 fixed_t K_GetExpAdjustment(player_t *player);
 
+UINT16 K_GetDisplayEXP(player_t *player);
+
 UINT32 K_GetNumGradingPoints(void);
 
 #ifdef __cplusplus

src/k_tally.cpp

@@ -343,8 +343,13 @@ void level_tally_t::Init(player_t *player)
 
 		if ((gametypes[gt]->rules & GTR_CIRCUIT) == GTR_CIRCUIT)
 		{
-			laps = std::clamp(FixedMul(std::max(stplyr->exp, FRACUNIT/2), (500/K_GetNumGradingPoints())*player->gradingpointnum), 0, 999);
-			totalLaps = 500;
+			UINT16 displayEXP = K_GetDisplayEXP(player);
+
+			if (displayEXP != UINT16_MAX)
+			{
+				laps = displayEXP;
+				totalLaps = 500;
+			}
 		}
 
 		if (battleprisons)