Fixed all the problem reported by varcheck (unused variables)

Author: Mattia Bertorello

Diff for: .golangci.yml

@@ -28,6 +28,4 @@ linters:
   - lll
   - maligned
   - megacheck
-  - prealloc
   - unparam
-  - varcheck

Diff for: commands/config/dump.go

@@ -38,10 +38,11 @@ func initDumpCommand() *cobra.Command {
 	}
 }
 
-var dumpFlags struct {
-	_default bool   // If false, ask questions to the user about setting configuration properties, otherwise use default configuration.
-	location string // The custom location of the file to create.
-}
+// This struct is unused
+//var dumpFlags struct {
+//	_default bool   // If false, ask questions to the user about setting configuration properties, otherwise use default configuration.
+//	location string // The custom location of the file to create.
+//}
 
 func runDumpCommand(cmd *cobra.Command, args []string) {
 	logrus.Info("Executing `arduino config dump`")

Diff for: commands/lib/uninstall.go

@@ -27,10 +27,11 @@ import (
 	"github.com/spf13/cobra"
 )
 
-const (
-	versionAll    string = "all"
-	versionLatest string = "latest"
-)
+// These const are unused
+//const (
+//	versionAll    string = "all"
+//	versionLatest string = "latest"
+//)
 
 func initUninstallCommand() *cobra.Command {
 	uninstallCommand := &cobra.Command{

Diff for: common/formatter/formatter.go

@@ -42,8 +42,6 @@ var defaultFormatter Formatter
 
 var logger *logrus.Logger
 
-var debug bool
-
 func init() {
 	formatters = make(map[string]Formatter, 2)
 	AddCustomFormatter("text", &TextFormatter{})