This commit adds error handling for the `f.Close()` errors when
we write the SBOM. Errors on close for RW fds are rare but we
should handle them so we return the result of `f.Close()` now
when returning in sbomWriter(). We still keep the `defer f.Close()`
to ensure we do not leak file descriptors when e.g. `io.Copy()`
fails. In the "happy" case f is closed without an error and
then the defer f.Close() runs and will error with "ErrClosed"
but we can ignore that.
An alternative implementaiton might be:
```golang
func sbomWriter(outputDir, filename string, content io.Reader) (err error) {
...
f, err := os.Create(p)
if err != nil {
return err
}
defer func() { err = errors.Join(err, f.Close()) }()
...
return nil
}
```
no super strong opinion here.
Thanks to Flo for finding this issues!
c829e60649