video_core: Modify astc texture decode error fill value

src/video_core/host_shaders/astc_decoder.comp

@@ -1065,7 +1065,7 @@ TexelWeightParams DecodeBlockInfo() {
 void FillError(ivec3 coord) {
     for (uint j = 0; j < block_dims.y; j++) {
         for (uint i = 0; i < block_dims.x; i++) {
-            imageStore(dest_image, coord + ivec3(i, j, 0), vec4(1.0, 1.0, 0.0, 1.0));
+            imageStore(dest_image, coord + ivec3(i, j, 0), vec4(0.0, 0.0, 0.0, 0.0));
         }
     }
 }

src/video_core/textures/astc.cpp

@@ -1411,7 +1411,7 @@ static void FillVoidExtentLDR(InputBitStream& strm, std::span<u32> outBuf, u32 b
 static void FillError(std::span<u32> outBuf, u32 blockWidth, u32 blockHeight) {
     for (u32 j = 0; j < blockHeight; j++) {
         for (u32 i = 0; i < blockWidth; i++) {
-            outBuf[j * blockWidth + i] = 0xFFFF00FF;
+            outBuf[j * blockWidth + i] = 0x00000000;
         }
     }
 }