More verbose error messages; make sure that a NULL attribute value is accepted by all field types

Core/ComplexField/EzBinaryFile.php

@@ -16,7 +16,10 @@ class EzBinaryFile extends AbstractComplexField implements ComplexFieldInterface
     {
         $mimeType = '';
         $fileName = '';
-        if (is_string($fieldValue)) {
+
+        if ($fieldValue === null) {
+            return new BinaryFileValue();
+        } if (is_string($fieldValue)) {
             $filePath = $fieldValue;
         } else {
             $filePath = $fieldValue['path'];

Core/ComplexField/EzImage.php

@@ -18,7 +18,10 @@ class EzImage extends AbstractComplexField implements ComplexFieldInterface
     {
         $altText = '';
         $fileName = '';
-        if (is_string($fieldValue)) {
+
+        if ($fieldValue === null) {
+            return new ImageValue();
+        } else if (is_string($fieldValue)) {
             $filePath = $fieldValue;
         } else {
             $filePath = $fieldValue['path'];

Core/ComplexField/EzRelation.php

@@ -32,6 +32,10 @@ class EzRelation extends AbstractComplexField implements ComplexFieldInterface
             $id = $fieldValue;
         }
 
+        if ($id === null) {
+            return new Value();
+        }
+
         // 1. resolve relations
         $id = $this->referenceResolver->resolveReference($id);
         // 2. resolve remote ids

Core/MigrationService.php

@@ -351,6 +351,11 @@ class MigrationService
                 }
             }
         }
+
+        while (($e = $e->getPrevious()) != null) {
+            $message .= "\n" . $e->getMessage();
+        }
+
         return $message;
     }
 }

Tests/dsl/good/UnitTestOK004_content.yml

@@ -207,6 +207,36 @@
             destinationContentId: 'reference:kmb_test_2_1'
         - ezobjectrelationlist:
             destinationContentIds: [ 'reference:kmb_test_2_1', 'reference:kmb_test_2_2' ]
+
+-
+    type: content
+    mode: create
+    content_type: kmb_test_2
+    parent_location: 2
+    attributes:
+        ezstring: null
+        ezauthor: null
+        ezbinaryfile: null
+        ezboolean: null
+        ezcountry: null
+        ezdatetime: null
+        ezdate: null
+        ezemail: null
+        ezfloat: null
+        ezimage: null
+        ezinteger: null
+        ezisbn: null
+        ezkeyword: null
+        ezmedia: null
+        ezobjectrelation: null
+        ezobjectrelationlist: null
+        ezrichtext: null
+        eztext: null
+        eztime: null
+        ezurl: null
+        ezuser: null
+        ezxmltext: null
+
 -
     type: content
     mode: update