Fixed uninitialized memory due to missing returns in canary

Functions which are suppose to crash on non canary builds usually don't return anything which lead to uninitialized memory being used.

src/video_core/morton.cpp

@@ -192,6 +192,7 @@ static MortonCopyFn GetSwizzleFunction(MortonSwizzleMode mode, Surface::PixelFor
         return linear_to_morton_fns[static_cast<std::size_t>(format)];
     }
     UNREACHABLE();
+    return morton_to_linear_fns[static_cast<std::size_t>(format)];
 }
 
 /// 8x8 Z-Order coordinate from 2D coordinates