Add check for non struct types to fetchField (#794)

Co-authored-by: yigitkanbalci <[email protected]>

Author: yigitkanbalci

checker/checker_test.go

@@ -1,6 +1,7 @@
 package checker_test
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 	"regexp"
@@ -1078,6 +1079,30 @@ func TestCheck_builtin_without_call(t *testing.T) {
 	}
 }
 
+func TestCheck_EmbeddedInterface(t *testing.T) {
+	t.Run("embedded interface lookup returns compile-error not panic", func(t *testing.T) {
+		type Env struct {
+			context.Context
+			Country string
+		}
+		type Wrapper struct {
+			Ctx Env
+		}
+
+		config := conf.New(Wrapper{
+			Ctx: Env{
+				Context: context.Background(),
+				Country: "TR",
+			},
+		})
+		expr.WithContext("Ctx")(config)
+
+		_, err := checker.ParseCheck("Ctx.C", config)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "has no field C")
+	})
+}
+
 func TestCheck_types(t *testing.T) {
 	env := types.Map{
 		"foo": types.Map{

checker/nature/utils.go

@@ -14,6 +14,11 @@ func fieldName(field reflect.StructField) string {
 }
 
 func fetchField(t reflect.Type, name string) (reflect.StructField, bool) {
+	// If t is not a struct, early return.
+	if t.Kind() != reflect.Struct {
+		return reflect.StructField{}, false
+	}
+
 	// First check all structs fields.
 	for i := 0; i < t.NumField(); i++ {
 		field := t.Field(i)