builder/remotecontext: remove unused named and "naked" returns

Also renamed some vars for clarity, renamed a error-returns to prevent
shadowing, and fixed some linter warnings about unhandled errors.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/image/build/internal/git/gitutils.go

@@ -46,7 +46,7 @@ func Clone(remoteURL string, opts ...CloneOption) (string, error) {
 	return repo.clone()
 }
 
-func (repo gitRepo) clone() (checkoutDir string, err error) {
+func (repo gitRepo) clone() (checkoutDir string, retErr error) {
 	fetch := fetchArgs(repo.remote, repo.ref)
 
 	root, err := os.MkdirTemp("", "docker-build-git")
@@ -55,8 +55,8 @@ func (repo gitRepo) clone() (checkoutDir string, err error) {
 	}
 
 	defer func() {
-		if err != nil {
-			os.RemoveAll(root)
+		if retErr != nil {
+			_ = os.RemoveAll(root)
 		}
 	}()