`predict` uses depreciated array recycling

[nlubock]

> library(drc)
> spinach.model1 <- drm(SLOPE~DOSE, CURVE, data = spinach, fct = LL.4())
> predict(spinach.model1, data.frame(dose=2, CURVE=c("1", "2", "3")), 
+         interval = "confidence")
     Prediction     Lower     Upper
[1,]  0.9048476 0.8552178 0.9544775
[2,]  0.4208307 0.3626741 0.4789873
[3,]  0.5581673 0.4971838 0.6191509
Warning messages:
1: In (tquan * sqrt(varVal + sumObjRV)) * c(-1, 1) :
  Recycling array of length 1 in array-vector arithmetic is deprecated.
  Use c() or as.vector() instead.

2: In (tquan * sqrt(varVal + sumObjRV)) * c(-1, 1) :
  Recycling array of length 1 in array-vector arithmetic is deprecated.
  Use c() or as.vector() instead.

3: In (tquan * sqrt(varVal + sumObjRV)) * c(-1, 1) :
  Recycling array of length 1 in array-vector arithmetic is deprecated.
  Use c() or as.vector() instead.

Relevant SessionInfo:

R version 3.6.3 (2020-02-29)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Debian GNU/Linux 10 (buster)

Matrix products: default
BLAS/LAPACK: /usr/lib/x86_64-linux-gnu/libopenblasp-r0.3.5.so

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

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

other attached packages:
[1] drc_3.0-1     MASS_7.3-51.5

loaded via a namespace (and not attached):
 [1] zip_2.1.1         Rcpp_1.0.4        cellranger_1.1.0 
 [4] pillar_1.4.7      compiler_3.6.3    forcats_0.5.0    
 [7] tools_3.6.3       lifecycle_0.2.0   tibble_3.0.4     
[10] lattice_0.20-38   pkgconfig_2.0.3   rlang_0.4.9      
[13] openxlsx_4.2.3    Matrix_1.2-18     rstudioapi_0.13  
[16] curl_4.3          mvtnorm_1.1-1     haven_2.2.0      
[19] rio_0.5.16        vctrs_0.3.5       gtools_3.8.2     
[22] hms_0.5.3         grid_3.6.3        data.table_1.12.8
[25] R6_2.5.0          plotrix_3.7-8     readxl_1.3.1     
[28] survival_3.1-8    foreign_0.8-75    multcomp_1.4-15  
[31] TH.data_1.0-10    carData_3.0-4     car_3.0-10       
[34] magrittr_2.0.1    scales_1.1.0      codetools_0.2-16 
[37] ellipsis_0.3.1    splines_3.6.3     rsconnect_0.8.16 
[40] abind_1.4-5       colorspace_1.4-1  sandwich_3.0-0   
[43] stringi_1.5.3     munsell_0.5.0     crayon_1.3.4     
[46] zoo_1.8-8   

[ryandward]

How's this coming along?

[KonstantinLang]

@daniel-gerhard, @christian-ritz, can you please take care of this issue.