Shiny Client Errors: Cannot read properties of null (reading 'deps')

[pawelru]

https://shinylive.io/r/editor/#code=NobwRAdghgtgpmAXGKAHVA6ASmANGAYwHsIAXOMpMAGwEsAjAJykYE8AKcqajGIgEwCu1OAGcMAcwpxm1AJQAdCHSYsOo1CwDWdCHEUQlaVAAIAPAFoTtCLVLslJk-yikoJgLwmu1APou3dgBJLCCAZU9rRlpROVxHEz4hEVFIpOExBwgnJ1IYXwA3FlooehFfJiIAd1EZBzAANWLSkRMAIUZq2sYFMAMnAwMlUQALG1YAQXR2YwASQVpcEznugpkDMABfAF0gA

I think it's due to this change in the htmlwidgets: r-wasm/htmlwidgets@892798f

console log

shiny.min.js:2 TypeError: Cannot read properties of null (reading 'deps')
    at shinyBinding.renderValue (htmlwidgets.js:515:44)
    at e.<anonymous> (shiny.min.js:2:174316)
    at m (shiny.min.js:2:166780)
    at Generator.<anonymous> (shiny.min.js:2:168103)
    at Generator.next (shiny.min.js:2:167139)
    at R_ (shiny.min.js:2:172750)
    at s (shiny.min.js:2:172948)
    at shiny.min.js:2:173009
    at new Promise (<anonymous>)
    at e.<anonymous> (shiny.min.js:2:172889)

When I enter the JS debugger I can see the following:

data is null thus data.deps throws

Outside of shinylive everything is fine. Entering debugger in the same place does not show null value.

I'm trying to create a base shiny example for this to debug this easier but the example above shows that it is possible to have null value there so it would make sense to handle this somehow.

I have seen #124 but adding loading dependency from external CDS does not help.

[pawelru]

similar issue: r-wasm/webr#330

[pawelru]

Minimal reprex

https://shinylive.io/r/editor/#code=NobwRAdghgtgpmAXGKAHVA6ASmANGAYwHsIAXOMpMAGwEsAjAJykYE8AKAZwAtaJWAlAB0IdJiw71OY4aIbM27ACIAVWSICutAAQAeALTbUUAOZwA+p1oATOPRbsR27Vdv3G2gLwubdh0+dtAm44AgBreiIADwBJCFQNUkcIQMC+BNIY6y9tITBGOABHPNwA1OooejhqHLyCwu0ANyhqDTgSssDm1rgcgDEAQQAZAGUAUU7ZZwFSlO1VAHlEjPYiZcSs2rAovNl1CE44RkajvUMAMw0IAlJaEnZ0xNxtNdIMgW0QANeMgBIos7aAoQWyMVTsL5zZz1B7xRK-epTNKMWicAIAX1k6JEIh4fFYA3Q7C0OS0z0Ox1O3gpJ0YsjA6IAukA

library(shiny)
library(bslib)
library(DT)

ui <- page_sidebar(
  sidebar = sidebar(
    checkboxInput(
      inputId = "req",
      label = "req value",
      value = FALSE
    )
  ),
  DTOutput(outputId = "x")
)

server <- function(input, output) {
  output$x <- renderDT({
    req(input$req)
    iris
  })
}

shinyApp(ui = ui, server = server)

[georgestagg]

I believe I have tracked down the underlying issue. That is, I now know how and why the problematic null object is being generated.

The issue is related to the patches made to webR's distribution of Shiny so that it can work well under WebAssembly. I have fixed the problem and made a new release of the package at https://github.com/r-wasm/shiny/releases.

With this latest build, the example app works without generating any errors:

Shinylive won't automatically pick up the change, but I will include upgrading the Shiny R package as part of some other work I am currently undertaking. Once that work has all been merged, it should fix the issue on shinylive.io etc.

[georgestagg]

The above reprex (here) should now run successfully without errors on shinylive.io when toggling the req() switch.

The associated PR for the R Shinylive package to include the latest version of the assets is here: #131