DndReadAloud and DndSidebar fail when the optional argument is omitted

[massimobarbieri]

Dear developer,
With TeX Live 2026, environments such as DndReadAloud and DndSidebar fail when the optional argument is omitted. pgfkeys reports /tcb/\NoValue. As a workaround, using an explicit empty optional argument (\begin{DndReadAloud}[] and \begin{DndSidebar}[]{Title}) avoids the error. This appears to be an incompatibility with recent LaTeX/xparse handling of optional arguments.
Thanks for your great work!

[massimobarbieri]

Please, see pull request about this issue