`copy` permits using to mix `[]byte` and `string` arguments without
explicit conversion. I removed explicit conversion to make the code simpler.
Signed-off-by: Iskander Sharipov <quasilyte@gmail.com>
megacheck, gosimple and unused has been deprecated and subsumed by
staticcheck. And staticcheck also has been upgraded. we need to update
code for the linter issue.
close: #2945
Signed-off-by: Wei Fu <fuweid89@gmail.com>
