Print valid enum values when none match

pkg/controller/direct/monitoring/maputils.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"strconv"
+	"strings"
 	"time"
 
 	"google.golang.org/protobuf/reflect/protoreflect"
@@ -72,7 +73,13 @@ func Enum_ToProto[U ProtoEnum](ctx *MapContext, in *string) U {
 		}
 	}
 
-	ctx.Errorf("unknown enum value %q", in)
+	var validValues []string
+	for i := 0; i < n; i++ {
+		value := descriptor.Values().Get(i)
+		validValues = append(validValues, string(value.Name()))
+	}
+
+	ctx.Errorf("unknown enum value %q for %v (valid values are %v)", inValue, descriptor.FullName(), strings.Join(validValues, ", "))
 	return 0
 }