fix(json): JsonNormalizedRenderer now renders only fields that can be converted to json

changelog.txt

 # Changelog
 
+## [2.3.1] - 2020-10-20
+### Fixed
+- JsonNormalizedRenderer now renders only fields that can be converted to json
+
 ## [2.3] - 2020-10-15
 ### Added
 - Added Timepicker field

src/Renderer/JsonNormalizedRenderer.php

@@ -58,8 +58,9 @@ class JsonNormalizedRenderer implements FieldRenderer {
 					];
 				}
 			}
-
-			$rendered_fields[] = $rendered;
+			if (json_encode($rendered) !== false) {
+				$rendered_fields[] = $rendered;
+			}
 		}
 
 		return $rendered_fields;