cast the type map expression to the property type

Author: lbargaoanu

src/AutoMapper/Execution/ExpressionBuilder.cs

@@ -87,14 +87,13 @@ public static Expression MapExpression(this IGlobalConfiguration configuration,
             {
                 mapExpression = mapper.MapExpression(configuration, profileMap, memberMap, source, destination);
                 nullCheck = mapExpression != source;
-                mapExpression = ToType(mapExpression, typePair.DestinationType);
             }
             else
             {
                 nullCheck = true;
             }
         }
-        mapExpression ??= ContextMap(typePair, source, destination, memberMap);
+        mapExpression = mapExpression == null ? ContextMap(typePair, source, destination, memberMap) : ToType(mapExpression, typePair.DestinationType);
         return nullCheck ? configuration.NullCheckSource(profileMap, source, destination, mapExpression, memberMap) : mapExpression;
     }
     public static Expression NullCheckSource(this IGlobalConfiguration configuration, ProfileMap profileMap, Expression source, Expression destination,

src/UnitTests/TypeConverters.cs

@@ -1,5 +1,26 @@
 namespace AutoMapper.UnitTests.CustomMapping;
-
+public class StringToEnumConverter : AutoMapperSpecBase
+{
+    class Source
+    {
+        public string Enum { get; set; }
+    }
+    class Destination
+    {
+        public ConsoleColor Enum { get; set; }
+    }
+    protected override MapperConfiguration CreateConfiguration() => new(c => 
+    { 
+        c.CreateMap<string, Enum>().ConvertUsing(s => ConsoleColor.DarkCyan);
+        c.CreateMap<Source, Destination>();
+    });
+    [Fact]
+    public void Should_work()
+    {
+        Map<ConsoleColor>("").ShouldBe(ConsoleColor.DarkCyan);
+        Map<Destination>(new Source()).Enum.ShouldBe(ConsoleColor.DarkCyan);
+    }
+}
 public class NullableConverter : AutoMapperSpecBase
 {
     public enum GreekLetters