Add missing validation in copy_texture_to-Buffer. (#2958)

Author: nical

CHANGELOG.md

@@ -113,6 +113,7 @@ the same every time it is rendered, we now warn if it is missing.
 - Validate the number of color attachments in `create_render_pipeline` by @nical in [#2913](https://github.com/gfx-rs/wgpu/pull/2913)
 - Validate against the maximum binding index in `create_bind_group_layout` by @nical in [#2892](https://github.com/gfx-rs/wgpu/pull/2892)
 - Validate that map_async's range is not negative by @nical in [#2938](https://github.com/gfx-rs/wgpu/pull/2938)
+- Validate the sample count and mip level in `copy_texture_to_buffer` by @nical in [#2958](https://github.com/gfx-rs/wgpu/pull/2958)
 
 #### DX12
 - `DownlevelCapabilities::default()` now returns the `ANISOTROPIC_FILTERING` flag set to true so DX12 lists `ANISOTROPIC_FILTERING` as true again by @cwfitzgerald in [#2851](https://github.com/gfx-rs/wgpu/pull/2851)

wgpu-core/src/command/transfer.rs

@@ -109,6 +109,10 @@ pub enum TransferError {
     MemoryInitFailure(#[from] super::ClearError),
     #[error("Cannot encode this copy because of a missing downelevel flag")]
     MissingDownlevelFlags(#[from] MissingDownlevelFlags),
+    #[error("Source texture sample count must be 1, got {sample_count}")]
+    InvalidSampleCount { sample_count: u32 },
+    #[error("Requested mip level {requested} does no exist (count: {count})")]
+    InvalidMipLevel { requested: u32, count: u32 },
 }
 
 impl PrettyError for TransferError {
@@ -794,6 +798,19 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
         if !src_texture.desc.usage.contains(TextureUsages::COPY_SRC) {
             return Err(TransferError::MissingCopySrcUsageFlag.into());
         }
+        if src_texture.desc.sample_count != 1 {
+            return Err(TransferError::InvalidSampleCount {
+                sample_count: src_texture.desc.sample_count,
+            }
+            .into());
+        }
+        if source.mip_level >= src_texture.desc.mip_level_count {
+            return Err(TransferError::InvalidMipLevel {
+                requested: source.mip_level,
+                count: src_texture.desc.mip_level_count,
+            }
+            .into());
+        }
         let src_barrier = src_pending.map(|pending| pending.into_hal(src_texture));
 
         let (dst_buffer, dst_pending) = cmd_buf