Check argument sanity in w_ParticleSystem_setColors.

src/modules/graphics/opengl/wrap_ParticleSystem.cpp

@@ -204,27 +204,32 @@ namespace opengl
 	int w_ParticleSystem_setColors(lua_State * L)
 	{
 		ParticleSystem * t = luax_checkparticlesystem(L, 1);
-		size_t nColors = (lua_gettop(L) - 1) / 4;
+		int cargs = lua_gettop(L) - 1;
+		size_t nColors = (cargs + 3) / 4; // nColors = ceil(color_args / 4)
+		if (cargs % 4 != 0 || cargs == 0)
+			return luaL_error(L, "Expected red, green, blue, and alpha. Only got %d of 4 components.", cargs % 4);
 
 		if (nColors > 8)
 			return luaL_error(L, "At most eight (8) colors may be used.");
 
 		if (nColors == 1)
 		{
-			t->setColor(Color(luaL_checkint(L,2),
-						luaL_checkint(L,3),
-						luaL_checkint(L,4),
-						luaL_checkint(L,5)));
+			int r = luaL_checkint(L, 2);
+			int g = luaL_checkint(L, 3);
+			int b = luaL_checkint(L, 4);
+			int a = luaL_checkint(L, 5);
+			t->setColor(Color(r,g,b,a));
 		}
 		else
 		{
 			std::vector<Color> colors(nColors);
 			for (size_t i = 0; i < nColors; ++i)
 			{
-				colors[i] = Color(luaL_checkint(L, 1 + i*4 + 1),
-						luaL_checkint(L, 1 + i*4 + 2),
-						luaL_checkint(L, 1 + i*4 + 3),
-						luaL_checkint(L, 1 + i*4 + 4));
+				int r = luaL_checkint(L, 1 + i*4 + 1);
+				int g = luaL_checkint(L, 1 + i*4 + 2);
+				int b = luaL_checkint(L, 1 + i*4 + 3);
+				int a = luaL_checkint(L, 1 + i*4 + 4);
+				colors[i] = Color(r,g,b,a);
 			}
 			t->setColor(colors);
 		}