Errors in show method for Juno plot pane are swallowed

[yha]

MWE:

using Interact
struct A end
Base.show(io::IO, ::MIME"image/png", ::A) = error()
@manipulate for a=1:5
    a == 5 ? A() : a
end

When run inside Juno, and the slider is moved to 5, it stops updating, but the error is not reported.
This affects rendering of plots if there's a mistake that prevents it from being shown, e.g.

using Plots
@manipulate for i=1:5
    plot([0],title=i)
end

fails with no error message.