[widgets][editors] Don't return empty description in json dump

The field is optional

beat/editor/test/test_editors.py

@@ -109,10 +109,7 @@ class TestMockEditor:
         field.format_name = "value32"
         field.format_type = "float32"
 
-        assert widget.dump_json() == {
-            "field": {"value32": "float32"},
-            "description": "",
-        }
+        assert widget.dump_json() == {"field": {"value32": "float32"}}
 
         qtbot.mouseClick(widget.add_field_button, QtCore.Qt.LeftButton)
         fields = widget.findChildren(FieldWidget)
@@ -125,6 +122,5 @@ class TestMockEditor:
         field.format_type = "float64"
 
         assert widget.dump_json() == {
-            "field": {"value32": "float32", "value64": "float64"},
-            "description": "",
+            "field": {"value32": "float32", "value64": "float64"}
         }

beat/editor/widgets/editor.py

@@ -152,7 +152,11 @@ class AbstractAssetEditor(QWidget):
     def dump_json(self):
         """Returns the json representation of the asset"""
 
-        json_data = {"description": self.description_lineedit.text()}
+        json_data = {}
+
+        description = self.description_lineedit.text()
+        if description:
+            json_data["description"] = description
 
         json_data.update(self._dump_json())
         return json_data