Fix `make lint` (golangci-lint) issues for `internal/handler/exec.go` and `internal/handler/exec_test.go`

Closes #719

See merge request !1012



Merged-by: Ash McKenzie <amckenzie@gitlab.com>
Approved-by: Ash McKenzie <amckenzie@gitlab.com>
Co-authored-by: gaurav.marwal <gauravmarwal@gmail.com>