[Build] Fix build errors on ESP8266

src/src/Helpers/TaskValuesWriterHelper.cpp

@@ -214,10 +214,12 @@ void TaskValuesWriterHelper::pluginWebformShowValue()
     addHtmlDiv(F("div_br"));
   }
 
+#if FEATURE_STRING_VARIABLES
   if (hasPresentation) { value = presentation; }
   else if (!uom.isEmpty()) {
     value += concat(' ', uom);
   }
+#endif
 
   String valName_tmp(valName);
 

src/src/WebServer/JSON.cpp

@@ -638,12 +638,13 @@ void handle_json_stream_task_value_data(TaskValuesWriterHelper*data)
       writer->write(kv);
     }
 # endif // if FEATURE_STRING_VARIABLES
-
+#if FEATURE_TASKVALUE_UNIT_OF_MEASURE
     if (!data->uom.isEmpty()) {
       KeyValueStruct kv(F("UoM"), data->uom);
       kv.setID(data->uom_id);
       writer->write(kv);
     }
+#endif
   }
 }