Merge branch 'image_crash' of https://github.com/Randalphwa/wxWidgets

Don't crash in wxImage::InitAlpha() if it's called on an empty image
and avoid calling it in this case.

See #24260.

src/common/image.cpp

@@ -2185,6 +2185,8 @@ unsigned char *wxImage::GetAlpha() const
 
 void wxImage::InitAlpha()
 {
+    wxCHECK_RET( IsOk(), wxT("invalid image") );
+
     wxCHECK_RET( !HasAlpha(), wxT("image already has an alpha channel") );
 
     // initialize memory for alpha channel

src/msw/imaglist.cpp

@@ -167,6 +167,12 @@ void
 wxImageList::GetImageListBitmaps(wxMSWBitmaps& bitmaps,
                                  const wxBitmap& bitmap, const wxBitmap& mask)
 {
+    if (!bitmap.IsOk())
+    {
+        // We can't do anything with an invalid bitmap.
+        return;
+    }
+
     // This can be overwritten below if we need to modify the bitmap, but it
     // doesn't cost anything to initialize the bitmap with this HBITMAP.
     bitmaps.hbmp = GetHbitmapOf(bitmap);