make sure soap doesn't crash when messed with in the console

src/graphics/Renderer.cpp

@@ -1365,7 +1365,7 @@ void Renderer::render_parts()
 				{
 					if (t==PT_SOAP)
 					{
-						if ((parts[i].ctype&7) == 7)
+						if ((parts[i].ctype&7) == 7 && parts[i].tmp >= 0 && parts[i].tmp < NPART && parts[i].tmp2 >= 0 && parts[i].tmp2 < NPART)
 							draw_line(nx, ny, (int)(parts[parts[i].tmp].x+0.5f), (int)(parts[parts[i].tmp].y+0.5f), colr, colg, colb, cola);
 					}
 				}

src/simulation/elements/SOAP.cpp

@@ -104,6 +104,11 @@ int Element_SOAP::update(UPDATE_FUNC_ARGS)
 	{
 		if (parts[i].temp>FREEZING)
 		{
+			if (parts[i].tmp < 0 || parts[i].tmp >= NPART || parts[i].tmp2 < 0 || parts[i].tmp2 >= NPART)
+			{
+				parts[i].tmp = parts[i].tmp2 = parts[i].ctype = 0;
+				return 0;
+			}
 			if (parts[i].life<=0)
 			{
 				//if only connected on one side