add a mipmap check here ig

src/hardware/hw_cache.c

@@ -74,6 +74,9 @@ static void HWR_DrawColumnInCache(const column_t *patchcol, UINT8 *block, GLMipm
 
 	(void)patchheight; // This parameter is unused
 
+	if (!mipmap)
+		return;
+
 	if (originPatch) // originPatch can be NULL here, unlike in the software version
 		originy = originPatch->originy;
 
@@ -112,11 +115,11 @@ static void HWR_DrawColumnInCache(const column_t *patchcol, UINT8 *block, GLMipm
 			alpha = 0xFF;
 
 			// Make pixel transparent if chroma keyed
-			if ((mipmap->flags & TF_CHROMAKEYED) && (texel == HWR_PATCHES_CHROMAKEY_COLORINDEX))
+			if ((mipmap && mipmap->flags & TF_CHROMAKEYED) && (texel == HWR_PATCHES_CHROMAKEY_COLORINDEX))
 				alpha = 0x00;
 
 			//Hurdler: 25/04/2000: now support colormap in hardware mode
-			if (mipmap->colormap)
+			if (mipmap && mipmap->colormap)
 				texel = mipmap->colormap[texel];
 
 			// hope compiler will get this switch out of the loops (dreams...)