StorageBuffer logs cryptic error, when Item Type has wrong size.

[MonaMayrhofer]

Bevy version

v0.7.0 and main branch 18c6a7b

Operating system & version

Archlinux

What you did

Create a StorageBuffer of items of types like:

#[derive(AsStd430)]
struct NotInherentlyAligned {
    data: Vec3,
}

then call write_buffer

What you expected to happen

Buffer gets written to the queue without problems.

Internally:

• scratch gets resized to the size of the Std430 representation of the item type
• Writerwrites the Std430 representation to the scratch

What actually happened

Buffer gets partially written to the queue and logs an std::io::ErrorKind::WriteZero

Internally:

• scratch gets resized to the size of the item type (which is smaller than the Std430 representation due to missing padding)
• Writerwrites the Std430 representation to the scratch, which is too small, and therefore errors.

Additional information

All internal uses of StorageBuffer just happen to have data, which does not need to be padded to be aligned correctly.

I thew together a PR that should fix this (#4557)