fix plotly incongruity (to be polite)

[t-bltg]

Maybe fix #4583.

I don't like doing this (exceptions to the already complicated load / requires mechanism).

Can you test that it works @BeastyBlacksmith ?

[BeastyBlacksmith]

julia> using Plots; plotly(); plot(rand(10))
[ Info: Precompiling Plots [91a5bcdd-55d7-5caf-9e0b-520d859cae80]
┌ Warning: backend `GR` is not installed.
└ @ Plots ~/.julia/dev/Plots/src/backends.jl:33
[ Info: GR
[ Info: Precompiling PlotlyKaleido [f2990250-8cf9-495f-b13a-cce12b45703c]

This works. I'm a bit irritated by that warning though

[BeastyBlacksmith]

we might want to add a simple test with the plotly backend, that creates a html-file

[t-bltg]

I'm a bit irritated by that warning though

You mean the @warn "For saving to png with the `Plotly` backend `PlotlyBase` and `PlotlyKaleido` need to be installed." err ?

We can make it a @debug.

[BeastyBlacksmith]

I mean

┌ Warning: backend `GR` is not installed.
└ @ Plots ~/.julia/dev/Plots/src/backends.jl:33

[t-bltg]

we might want to add a simple test with the ploty backend, that creates a html-file

As I said, I'm not plotly competent at all, so if you have a test idea ...

[t-bltg]

Warning: backend GR is not installed.

How can that happen ? GR is a hard depedency of Plots, maybe run instantiate ?

[BeastyBlacksmith]

Warning: backend GR is not installed.

How can that happen ? GR is a hard depedency of Plots, maybe run instantiate ?

Hmm.. I had this, but it doesn't show up on CI. Must be my system then.

[codecov]

Codecov Report

Base: 90.64% // Head: 90.74% // Increases project coverage by +0.09% 🎉

Coverage data is based on head (cc3832f) compared to base (6e8c0de).
Patch coverage: 81.63% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4584      +/-   ##
==========================================
+ Coverage   90.64%   90.74%   +0.09%     
==========================================
  Files          41       41              
  Lines        8757     8765       +8     
==========================================
+ Hits         7938     7954      +16     
+ Misses        819      811       -8     

Impacted Files	Coverage Δ
src/Plots.jl	88.88% <ø> (ø)
src/backends.jl	81.81% <81.25%> (+0.31%)	⬆️
src/init.jl	100.00% <100.00%> (+26.66%)	⬆️

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[BeastyBlacksmith]

I mean

┌ Warning: backend `GR` is not installed.
└ @ Plots ~/.julia/dev/Plots/src/backends.jl:33

FWIW, I've seen that warning popping up in multiple occasions now, also on other peoples machines. It's working afterwards nevertheless, but it is irritating.

Secondly, I happened to notice that you can't use the plotlybase functionality if you haven't PlotlyKaleido installed, which ideally shouldn't be.

[t-bltg]

FWIW, I've seen that warning popping up in multiple occasions now, also on other peoples machines. It's working afterwards nevertheless, but it is irritating.

Maybe an environment stack issue. Could help if we had a reproducer.