使用shinyalert示例时遇错误：length=3强制转换为logical(1)致R会话崩溃

运行下方Shiny应用并点击Go按钮时，R会话崩溃，报错如下：

Warning : Error in &&: 'length = 3' in coercion to 'logical(1)'
  3: runApp
  2: print.shiny.appobj
  1: <Anonymous>

应用代码：

library(shiny)
library(shinyalert)

shinyApp(
  ui = fluidPage(
    actionButton("btn", "Go")
  ),
  server = function(input, output) {
    observeEvent(input$btn, {
      shinyalert(
        html = TRUE,
        text = tagList(
          numericInput("num", "Number", 10),
          "The square of the number is",
          textOutput("square", inline = TRUE)
        )
      )
    })

    output$square <- renderText({ input$num*input$num })
  }
)

会话信息：

> sessionInfo()
R version 4.3.0 (2023-04-21)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Linux Mint 20.3

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0 
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0

locale:
 [1] LC_CTYPE=fr_BE.UTF-8       LC_NUMERIC=C               LC_TIME=fr_BE.UTF-8       
 [4] LC_COLLATE=fr_BE.UTF-8     LC_MONETARY=fr_BE.UTF-8    LC_MESSAGES=fr_BE.UTF-8   
 [7] LC_PAPER=fr_BE.UTF-8       LC_NAME=C                  LC_ADDRESS=C              
[10] LC_TELEPHONE=C             LC_MEASUREMENT=fr_BE.UTF-8 LC_IDENTIFICATION=C        

time zone: Europe/Brussels
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base      

other attached packages:
[1] shinyalert_3.0.0 shiny_1.7.4     

loaded via a namespace (and not attached):
 [1] crayon_1.5.1     cli_3.6.1        knitr_1.42       rlang_1.1.1      xfun_0.39        promises_1.2.0.1
 [7] jsonlite_1.8.4   xtable_1.8-4     htmltools_0.5.5  httpuv_1.6.5     sass_0.4.6       jquerylib_0.1.4 
[13] ellipsis_0.3.2   fastmap_1.1.1    lifecycle_1.0.3  memoise_2.0.1    compiler_4.3.0   Rcpp_1.0.10     
[19] rstudioapi_0.14  later_1.3.0      digest_0.6.31    R6_2.5.1         commonmark_1.9.0 magrittr_2.0.3  
[25] bslib_0.4.2      uuid_1.1-0       tools_4.3.0      withr_2.5.0      mime_0.12        xml2_1.3.4      
[31] cachem_1.0.8    

当shinyalert设置html=TRUE时，text参数对应的tagList中不能直接包含普通字符串（如示例中的"The square of the number is"）。这类字符串会被解析为独立元素，导致shinyalert内部逻辑判断时，&&操作符接收到长度为3的向量，触发类型转换错误。

将普通文本用tags$span包裹，使其成为有效的HTML标签元素，确保tagList内所有元素都是Shiny/HTML标签。修改后的代码如下：

library(shiny)
library(shinyalert)

shinyApp(
  ui = fluidPage(
    actionButton("btn", "Go")
  ),
  server = function(input, output) {
    observeEvent(input$btn, {
      shinyalert(
        html = TRUE,
        text = tagList(
          numericInput("num", "Number", 10),
          tags$span("The square of the number is"),
          textOutput("square", inline = TRUE)
        )
      )
    })

    output$square <- renderText({ input$num*input$num })
  }
)

也可以用HTML()函数包裹文本，效果一致：

tags$span(HTML("The square of the number is"))

修改后点击Go按钮，就能正常弹出包含交互式输入和实时计算结果的弹窗，不会再触发崩溃错误。

内容的提问来源于stack exchange，提问作者Stéphane Laurent