Dialog fails since theme is undefined

[mkitti]

Describe the bug
Theme is undefined on this line in dialog
https://github.com/piever/InteractBase.jl/blob/0a91fe6d605cafcb27b1b9c15d5fea568fb187da/src/input.jl#L113

Original report here:
JuliaGizmos/Interact.jl#414

To Reproduce
See JuliaGizmos/Interact.jl#414

Expected behavior
theme should be defined.

Screenshots
See JuliaGizmos/Interact.jl#414

Version info (please complete the following information):

• include the output of versioninfo() and Pkg.status()
• how are you deploying the widgets? Jupyter Notebook/Lab, Juno, Blink or Mux?

Before opening an issue

• make sure you are on the latest release of InteractBase and try rebuilding it with Pkg.build("InteractBase")

If widgets do not appear

• test that your WebIO is correctly installed. Make sure you're on latest release and rebuild it with Pkg.build("WebIO")
• try a simple code to produce a slider: using WebIO; display(Node(:input, attributes = Dict("type" => "range")))
• if this doesn't produce a slider, your WebIO is not installed correctly and you may wish to open an issue at WebIO rather than here,

[mkitti]

Trace to #167 @rafaqz