Border radius uniformisation

We had a lot of radius 20, 22 and 24 which led to design
inconsistencies.  Set them all to 20.

Widgets/Sidebar/Config/SettingsModal.qml

@@ -22,7 +22,7 @@ PanelWindow {
     Rectangle {
         anchors.fill: parent
         color: Theme.backgroundPrimary
-        radius: 24
+        radius: 20
         z: 0
 
         ColumnLayout {

Widgets/Sidebar/Panel/BluetoothPanel.qml

@@ -90,7 +90,7 @@ Item {
         Rectangle {
             anchors.fill: parent
             color: Theme.backgroundPrimary
-            radius: 24
+            radius: 20
 
             ColumnLayout {
                 anchors.fill: parent

Widgets/Sidebar/Panel/WallpaperPanel.qml

@@ -40,7 +40,7 @@ PanelWindow {
     Rectangle {
         anchors.fill: parent
         color: Theme.backgroundPrimary
-        radius: 24
+        radius: 20
         ColumnLayout {
             anchors.fill: parent
             anchors.margins: 32

Widgets/Sidebar/Panel/WifiPanel.qml

@@ -482,7 +482,7 @@ Item {
         Rectangle {
             anchors.fill: parent
             color: Theme.backgroundPrimary
-            radius: 24
+            radius: 20
             ColumnLayout {
                 anchors.fill: parent
                 anchors.margins: 32
@@ -590,7 +590,7 @@ Item {
                             anchors.fill: parent
                             spacing: 4
                             boundsBehavior: Flickable.StopAtBounds
-                            model: Object.values(wifiLogic.networks)
+                            model: wifiLogic.networks ? Object.values(wifiLogic.networks) : null
                             delegate: Item {
                                 id: networkEntry