[GraphExplorer] fix camera so that graph is centered

src/Gargantext/Components/GraphExplorer/Resources.purs

@@ -153,7 +153,7 @@ drawGraphCpt = R.memo' $ here.component "graph" cpt where
                   -- Default camera: slightly de-zoom the graph to avoid
                   -- nodes sticking to the container borders
                   Nothing                           ->
-                    Sigma.updateCamera sig { ratio: 1.1, x: 0.0, y: 0.0 }
+                    Sigma.updateCamera sig { ratio: 1.1, x: 0.5, y: 0.5 }
 
                 -- Reload Sigma on Theme changes
                 -- TODO

src/Gargantext/Components/GraphExplorer/Types.purs

@@ -51,7 +51,7 @@ instance JSON.ReadForeign Node where
       Record.rename idP id_P $
       Record.rename typeP type_P $
       Record.rename x_coordP xP $
-      Record.rename y_coordP yP inst
+      Record.rename y_coordP yP $ inst
 instance JSON.WriteForeign Node where
   writeImpl (Node nd) = JSON.writeImpl $
                         Record.rename id_P idP $