exercise.diagnostics does not recognize "else if" (unexpected symbol 'if')

[Brunox13]

System details

Output of sessioninfo::session_info():

─ Session info ─────────────────────────────────────────────────────────────────────────────────────
 setting  value                       
 version  R version 4.0.2 (2020-06-22)
 os       macOS Catalina 10.15.6      
 system   x86_64, darwin17.0          
 ui       RStudio                     
 language (EN)                        
 collate  en_US.UTF-8                 
 ctype    en_US.UTF-8                 
 tz       America/New_York            
 date     2020-08-07                  

─ Packages ─────────────────────────────────────────────────────────────────────────────────────────
 package     * version    date       lib source                                      
 assertthat    0.2.1      2019-03-21 [1] CRAN (R 4.0.0)                              
 backports     1.1.8      2020-06-17 [1] CRAN (R 4.0.0)                              
 checkmate     2.0.0      2020-02-06 [1] CRAN (R 4.0.0)                              
 cli           2.0.2      2020-02-28 [1] CRAN (R 4.0.0)                              
 crayon        1.3.4      2017-09-16 [1] CRAN (R 4.0.0)                              
 digest        0.6.25     2020-02-23 [1] CRAN (R 4.0.0)                              
 evaluate      0.14       2019-05-28 [1] CRAN (R 4.0.0)                              
 fansi         0.4.1      2020-01-08 [1] CRAN (R 4.0.0)                              
 fastmap       1.0.1      2019-10-08 [1] CRAN (R 4.0.0)                              
 glue          1.4.1      2020-05-13 [1] CRAN (R 4.0.0)                              
 gradethis     0.1.0.9002 2020-07-09 [1] Github (rstudio-education/gradethis@c19a00a)
 htmltools     0.5.0      2020-06-16 [1] CRAN (R 4.0.0)                              
 htmlwidgets   1.5.1      2019-10-08 [1] CRAN (R 4.0.0)                              
 httpuv        1.5.4      2020-06-06 [1] CRAN (R 4.0.0)                              
 jsonlite      1.7.0      2020-06-25 [1] CRAN (R 4.0.0)                              
 knitr         1.29       2020-06-23 [1] CRAN (R 4.0.0)                              
 later         1.1.0.1    2020-06-05 [1] CRAN (R 4.0.0)                              
 learnr        0.10.1     2020-02-13 [1] CRAN (R 4.0.0)                              
 magrittr      1.5        2014-11-22 [1] CRAN (R 4.0.0)                              
 markdown      1.1        2019-08-07 [1] CRAN (R 4.0.0)                              
 mime          0.9        2020-02-04 [1] CRAN (R 4.0.0)                              
 promises      1.1.1      2020-06-09 [1] CRAN (R 4.0.0)                              
 R6            2.4.1      2019-11-12 [1] CRAN (R 4.0.0)                              
 Rcpp          1.0.5      2020-07-06 [1] CRAN (R 4.0.0)                              
 rlang         0.4.7      2020-07-09 [1] CRAN (R 4.0.2)                              
 rmarkdown     2.3        2020-06-18 [1] CRAN (R 4.0.0)                              
 rprojroot     1.3-2      2018-01-03 [1] CRAN (R 4.0.0)                              
 rsconnect     0.8.16     2019-12-13 [1] CRAN (R 4.0.0)                              
 rstudioapi    0.11       2020-02-07 [1] CRAN (R 4.0.0)                              
 sessioninfo   1.1.1      2018-11-05 [1] CRAN (R 4.0.2)                              
 shiny         1.5.0      2020-06-23 [1] CRAN (R 4.0.0)                              
 withr         2.2.0      2020-04-20 [1] CRAN (R 4.0.0)                              
 xfun          0.15       2020-06-21 [1] CRAN (R 4.0.0)                              
 xtable        1.8-4      2019-04-21 [1] CRAN (R 4.0.0)                              
 yaml          2.2.1      2020-02-01 [1] CRAN (R 4.0.0)                              

[1] /Library/Frameworks/R.framework/Versions/4.0/Resources/library

Example application or steps to reproduce the problem

     ---
     title: "Diagnostics Error"
     author: "Brunox13"
     output:
       learnr::tutorial:
         progressive: true
     runtime: shiny_prerendered
     ---
     
     ```{r setup, include = FALSE}
     library(learnr)
     ```
     
     ## Exercise Diagnostics Error
     
     ```{r 1, exercise = TRUE}
     
     ```

Describe the problem in detail

The code above works & renders fine. However, when a code like below is inserted inside an exercise, the code diagnostics gives an error: "unexpected symbol 'if'"

FB <- as.character(1:100)
for (i in 1:100){
    if (i%%15 == 0){
        FB[i] <-"FizzBuzz"
    } else if (i%%5==0) {
        FB[i] <- "Buzz"
    } else if (i%%3==0) {
        FB[i] <- "Fizz"
    } else {
        FB[i] <- i
    }
}
print(FB)

After clicking "Run Code," the code runs just fine, as shown below: