crosstalk::filter_slider() must go first, otherwise flexdashboard breaks?

The following crosstalk seems to break a flexdashboard:

---
output: 
  flexdashboard::flex_dashboard
---

```{r setup, include=FALSE}
library(flexdashboard)
library(crosstalk)
library(summarywidget)
set.seed(1)
df <- data.frame(
  x = seq(Sys.Date()-364, Sys.Date(), length.out = 99), 
  y = 1:99,
  group = gl(3,33)
) 
sd <- SharedData$new(df)
```

```{r}
filter_checkbox("chkb", "Checkbox", sd, ~group, inline = TRUE)
filter_slider("sldr", "Slider", sd, ~x)
summarywidget(sd, "sum", "y")
```

This works as expected - note that I only switched filter_checkbox and filter_slider:

---
output: 
  flexdashboard::flex_dashboard
---
```{r setup, include=FALSE}
library(flexdashboard)
library(crosstalk)
library(summarywidget)
set.seed(1)
df <- data.frame(
  x = seq(Sys.Date()-364, Sys.Date(), length.out = 99), 
  y = 1:99,
  group = gl(3,33)
)
sd <- SharedData$new(df)
```

```{r}
filter_slider("sldr", "Slider", sd, ~x)
filter_checkbox("chkb", "Checkbox", sd, ~group, inline = TRUE)
summarywidget(sd, "sum", "y")
```

My sessionInfo():

R version 3.3.2 (2016-10-31)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

locale:
[1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252    LC_MONETARY=German_Germany.1252 LC_NUMERIC=C                    LC_TIME=German_Germany.1252    

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

other attached packages:
 [1] htmltools_0.3.6          crosstalk_1.0.0          summarywidget_0.0.0.9000 forcats_0.2.0            rCharts_0.4.5            email_1.0               
 [7] stringi_1.1.2            magrittr_1.5             fastmatch_1.1-0          data.table_1.10.4        bit64_0.9-5              bit_1.1-12              
[13] lubridate_1.6.0          plotly_4.7.0.9000        flexdashboard_0.5        DT_0.2                   quantmod_0.4-8           TTR_0.23-1              
[19] xts_0.9-7                zoo_1.7-14               bindrcpp_0.1             dplyr_0.6.0              purrr_0.2.2.2            readr_1.0.0             
[25] tidyr_0.6.3              tibble_1.3.3             ggplot2_2.2.1.9000       tidyverse_1.0.0         

loaded via a namespace (and not attached):
 [1] lattice_0.20-34     colorspace_1.3-2    viridisLite_0.2.0   yaml_2.1.14         rlang_0.1.1         glue_1.0.0.9000     bindr_0.1           plyr_1.8.4         
 [9] stringr_1.1.0       munsell_0.4.3       gtable_0.2.0        htmlwidgets_0.8     evaluate_0.10       labeling_0.3        knitr_1.15.1        httpuv_1.3.3       
[17] Rcpp_0.12.11        xtable_1.8-2        backports_1.0.4     scales_0.4.1.9000   jsonlite_1.4        mime_0.5            digest_0.6.12       shiny_1.0.3        
[25] RJSONIO_1.3-0       grid_3.3.2          rprojroot_1.1       tools_3.3.2         lazyeval_0.2.0.9000 whisker_0.3-2       pkgconfig_2.0.1     rsconnect_0.7      
[33] assertthat_0.2.0    rmarkdown_1.3       httr_1.2.1          R6_2.2.1  

Reproduce the provided flexdashboard example with filter_checkbox(), filter_slider(), SharedData$new(), and summarywidget(), comparing the two filter orders. Start at the filter and dashboard rendering entry points, then verify that both orders produce the same working dashboard without breaking the layout or interactions.