diff --git a/src/main/webapp/resources/js/base/base.js b/src/main/webapp/resources/js/base/base.js
index aa1c135..7b395a9 100644
--- a/src/main/webapp/resources/js/base/base.js
+++ b/src/main/webapp/resources/js/base/base.js
@@ -769,7 +769,10 @@ class FormFields {
 					option.selected = option.value == value;
                 }
 				break;
-			case "span": input.innerHTML = value; break;
+			case "span":
+				if (value !== undefined)
+					input.innerHTML = value;
+				break;
 			case "img": input.src = value; break;
 			default: input.value = ifEmpty(value, ""); break;
 			}