refactor: Simplify and modernize loops (#1522)

* refactor: Simplify loops

* refactor: Modernize loops using range over int

---------

Co-authored-by: TwiN <twin@linux.com>

config/endpoint/condition.go

@@ -216,7 +216,7 @@ func sanitizeAndResolveNumericalWithContext(list []string, result *Result, conte
 
 func prettifyNumericalParameters(parameters []string, resolvedParameters []int64, operator string) string {
 	resolvedStrings := make([]string, 2)
-	for i := 0; i < 2; i++ {
+	for i := range 2 {
 		// Check if the parameter is a certificate or domain expiration placeholder
 		if parameters[i] == CertificateExpirationPlaceholder || parameters[i] == DomainExpirationPlaceholder {
 			// Format as duration string (convert milliseconds back to duration)

config/endpoint/endpoint.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"maps"
 	"math/rand"
 	"net"
 	"net/http"
@@ -489,9 +490,7 @@ func (e *Endpoint) call(result *Result) {
 	} else if endpointType == TypeWS {
 		wsHeaders := map[string]string{}
 		if e.Headers != nil {
-			for k, v := range e.Headers {
-				wsHeaders[k] = v
-			}
+			maps.Copy(wsHeaders, e.Headers)
 		}
 		if !hasHeader(wsHeaders, UserAgentHeader) {
 			wsHeaders[UserAgentHeader] = GatusUserAgent

config/endpoint/result.go

@@ -1,6 +1,7 @@
 package endpoint
 
 import (
+	"slices"
 	"time"
 )
 
@@ -66,11 +67,7 @@ type Result struct {
 // AddError adds an error to the result's list of errors.
 // It also ensures that there are no duplicates.
 func (r *Result) AddError(error string) {
-	for _, resultError := range r.Errors {
-		if resultError == error {
-			// If the error already exists, don't add it
-			return
-		}
+	if !slices.Contains(r.Errors, error) {
+		r.Errors = append(r.Errors, error+"")
 	}
-	r.Errors = append(r.Errors, error+"")
 }