remove unneeded constant

assets/src/scripts/monitoring-location/components/hydrograph/time-series-graph.js

@@ -106,13 +106,6 @@ const drawAllMedianPoints = function(elem, {visible, xscale, yscale, seriesPoint
 };
 
 const drawTitle = function(elem, store, siteNo, agencyCode, sitename, showMLName, showTooltip) {
-    const parameterDescription = (parameter) => {
-        if (parameter) {
-            return Object.prototype.hasOwnProperty.call(parameter, 'description') ?
-                parameter.description : 'No description available';
-        }
-    };
-
     let titleDiv = elem.append('div')
         .classed('time-series-graph-title', true);
 
@@ -126,7 +119,11 @@ const drawTitle = function(elem, store, siteNo, agencyCode, sitename, showMLName
         .call(link(store, (elem, {title, parameter}) => {
             elem.html(title);
             if (showTooltip) {
-                elem.call(appendInfoTooltip, parameterDescription(parameter), 'bottom');
+                elem.call(
+                    appendInfoTooltip,
+                    parameter ? parameter.description || 'No description available' : '',
+                    'bottom'
+                );
             }
         }, createStructuredSelector({
             title: getTitle('primary'),
@@ -137,7 +134,11 @@ const drawTitle = function(elem, store, siteNo, agencyCode, sitename, showMLName
         .call(link(store, (elem, {title, parameter}) => {
             elem.html(title);
             if (showTooltip && parameter) {
-                elem.call(appendInfoTooltip, parameterDescription(parameter), 'bottom');
+                elem.call(
+                    appendInfoTooltip,
+                    parameter ? parameter.description || 'No description available' : '',
+                    'bottom'
+                );
             }
         }, createStructuredSelector({
             title: getTitle('secondary'),