[FIX] web: cumulated graph single fix

Single value graph were not shown in cumulated graph.

This is due to unshift happening before the accumulator,
 leading to `undefined + X = NaN` for the value.

closes odoo/odoo#162385

X-original-commit: 121aa7e02235c5117bf6be6ccc6c8d6cefe6a744
Signed-off-by: Mathieu Duckerts-Antoine (dam) <dam@odoo.com>
Signed-off-by: Florian Damhaut (flda) <flda@odoo.com>

addons/web/static/src/views/graph/graph_renderer.js

@@ -373,6 +373,13 @@ export class GraphRenderer extends Component {
             } else {
                 dataset.borderColor = getColor(index, cookie.get("color_scheme"));
             }
+            if (cumulated) {
+                let accumulator = dataset.cumulatedStart;
+                dataset.data = dataset.data.map((value) => {
+                    accumulator += value;
+                    return accumulator;
+                });
+            }
             if (data.labels.length === 1) {
                 // shift of the real value to right. This is done to
                 // center the points in the chart. See data.labels below in
@@ -386,13 +393,6 @@ export class GraphRenderer extends Component {
             if (stacked) {
                 dataset.backgroundColor = hexToRGBA(dataset.borderColor, LINE_FILL_TRANSPARENCY);
             }
-            if (cumulated) {
-                let accumulator = dataset.cumulatedStart;
-                dataset.data = dataset.data.map((value) => {
-                    accumulator += value;
-                    return accumulator;
-                });
-            }
         }
         if (data.datasets.length === 1 && data.datasets[0].originIndex === 0) {
             const dataset = data.datasets[0];