Fix crash if Ctrl-C is pressed while no log is loaded

renderdocui/Windows/APIInspector.cs

@@ -265,6 +265,8 @@ namespace renderdocui.Windows
 
         private void apiEvents_KeyDown(object sender, KeyEventArgs e)
         {
+            if (!m_Core.LogLoaded) return;
+
             if (e.KeyCode == Keys.C && e.Control)
             {
                 string text = "";
@@ -279,6 +281,8 @@ namespace renderdocui.Windows
 
         private void callstack_KeyDown(object sender, KeyEventArgs e)
         {
+            if (!m_Core.LogLoaded) return;
+
             if (e.KeyCode == Keys.C && e.Control)
             {
                 string text = "";

renderdocui/Windows/Dialogs/ConstantBufferPreviewer.cs

@@ -255,6 +255,8 @@ namespace renderdocui.Controls
 
         private void variables_KeyDown(object sender, KeyEventArgs e)
         {
+            if (!m_Core.LogLoaded) return;
+        
             if (e.KeyCode == Keys.C && e.Control)
             {
                 int[] width = new int[] { 0, 0, 0 };

renderdocui/Windows/TextureViewer.cs

@@ -2229,6 +2229,8 @@ namespace renderdocui.Windows
                 Clipboard.SetText(texStatusDim.Text + " | " + statusLabel.Text);
             }
 
+            if (!m_Core.LogLoaded) return;
+
             if (e.KeyCode == Keys.Up && m_PickedPoint.Y > 0)
             {
                 m_PickedPoint = new Point(m_PickedPoint.X, m_PickedPoint.Y - 1);