added check if the digger is a nullptr (#4981)

Co-authored-by: 12xx12 <12xx12100@gmail.com>

src/Blocks/BlockIce.h

@@ -85,6 +85,7 @@ private:
 		const cEntity * a_Digger
 	) const override
 	{
+		UNUSED(a_Digger);
 		// If there's a solid block or a liquid underneath, convert to water, rather than air
 		if (a_BlockPos.y <= 0)
 		{

src/Blocks/BlockMobSpawner.h

@@ -61,6 +61,10 @@ private:
 		const cEntity * a_Digger
 	) const override
 	{
+		if (a_Digger == nullptr)
+		{
+			return;
+		}
 		if (!a_Digger->IsPlayer())
 		{
 			return;

src/Blocks/BlockOre.h

@@ -71,6 +71,10 @@ private:
 		const cEntity * a_Digger
 	) const override
 	{
+		if (a_Digger == nullptr)
+		{
+			return;
+		}
 		if (!a_Digger->IsPlayer())
 		{
 			return;