fix: [BUG] runtime error in (*routeRegexp).Match

regexp.go

@@ -187,6 +187,9 @@ type routeRegexp struct {
 
 // Match matches the regexp against the URL host or path.
 func (r *routeRegexp) Match(req *http.Request, match *RouteMatch) bool {
+	if r == nil {
+		return false
+	}
 	if r.regexpType == regexpTypeHost {
 		host := getHost(req)
 		if r.wildcardHostPort {

regexp_test.go

@@ -1,13 +1,26 @@
 package mux
 
 import (
+	"net/http"
 	"net/url"
 	"reflect"
 	"strconv"
 	"strings"
 	"testing"
 )
 
+func Test_routeRegexp_Match_NilReceiver(t *testing.T) {
+	var r *routeRegexp
+	req, _ := http.NewRequest("GET", "http://example.com/test", nil)
+	match := &RouteMatch{}
+
+	// Calling Match on a nil routeRegexp should not panic and return false
+	result := r.Match(req, match)
+	if result {
+		t.Error("Expected Match to return false for nil receiver, got true")
+	}
+}
+
 func Test_newRouteRegexp_Errors(t *testing.T) {
 	tests := []struct {
 		in, out string