Golangcilint in build pipeline and fix lint errors

- Fix bad permissions bits for files
- VPNSP is 'private internet access' instead of 'pia' (retro compatible)
- Check errors of deferred unsetEnv functions in params package
-  Other lint errors fixing and code simplifications

internal/params/firewall.go

@@ -1,29 +1,29 @@
-package params
-
-import (
-	"fmt"
-	"net"
-	"strings"
-)
-
-// GetExtraSubnets obtains the CIDR subnets from the comma separated list of the
-// environment variable EXTRA_SUBNETS
-func (p *paramsReader) GetExtraSubnets() (extraSubnets []net.IPNet, err error) {
-	s, err := p.envParams.GetEnv("EXTRA_SUBNETS")
-	if err != nil {
-		return nil, err
-	} else if s == "" {
-		return nil, nil
-	}
-	subnets := strings.Split(s, ",")
-	for _, subnet := range subnets {
-		_, cidr, err := net.ParseCIDR(subnet)
-		if err != nil {
-			return nil, fmt.Errorf("could not parse subnet %q from environment variable with key EXTRA_SUBNETS: %w", subnet, err)
-		} else if cidr == nil {
-			return nil, fmt.Errorf("parsing subnet %q resulted in a nil CIDR", subnet)
-		}
-		extraSubnets = append(extraSubnets, *cidr)
-	}
-	return extraSubnets, nil
-}
+package params
+
+import (
+	"fmt"
+	"net"
+	"strings"
+)
+
+// GetExtraSubnets obtains the CIDR subnets from the comma separated list of the
+// environment variable EXTRA_SUBNETS
+func (p *reader) GetExtraSubnets() (extraSubnets []net.IPNet, err error) {
+	s, err := p.envParams.GetEnv("EXTRA_SUBNETS")
+	if err != nil {
+		return nil, err
+	} else if s == "" {
+		return nil, nil
+	}
+	subnets := strings.Split(s, ",")
+	for _, subnet := range subnets {
+		_, cidr, err := net.ParseCIDR(subnet)
+		if err != nil {
+			return nil, fmt.Errorf("could not parse subnet %q from environment variable with key EXTRA_SUBNETS: %w", subnet, err)
+		} else if cidr == nil {
+			return nil, fmt.Errorf("parsing subnet %q resulted in a nil CIDR", subnet)
+		}
+		extraSubnets = append(extraSubnets, *cidr)
+	}
+	return extraSubnets, nil
+}