"error in process sentinel" whenever using %>% in an ESS R buffer

Question

Whenever I include a pipe (%>%) in a ESS R buffer, I start getting the following error repeatedly, with lags that make editing almost impossible:

error in process sentinel: Not enough arguments for format string

Here is a simple example. If I create a buffer with only this function:

f <- function(x) {
    x %>% sqrt
}

I get the following error backtrace when doing any edit that buffer (that's after doing M-x toggle-debug-on-error):

Debugger entered--Lisp error: (error "Not enough arguments for format string")
  format-message(" Error in cat(\"@@warning: @@\", e) : \n  argument 2 (type 'list') cannot be handled by 'cat'\nCalls: esslint ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous> -> cat\nIn addition: Warning message:\nIn file(con, \"r\") : cannot open file 'f <- function(x) {\n    x %>% sqrt \n}': No such file or directory\nExecution halted\n")
  apply(format-message " Error in cat(\"@@warning: @@\", e) : \n  argument 2 (type 'list') cannot be handled by 'cat'\nCalls: esslint ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous> -> cat\nIn addition: Warning message:\nIn file(con, \"r\") : cannot open file 'f <- function(x) {\n    x %>% sqrt \n}': No such file or directory\nExecution halted\n" nil)
  flymake--log-1(:warning ess-r-flymake " Error in cat(\"@@warning: @@\", e) : \n  argument 2 (type 'list') cannot be handled by 'cat'\nCalls: esslint ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous> -> cat\nIn addition: Warning message:\nIn file(con, \"r\") : cannot open file 'f <- function(x) {\n    x %>% sqrt \n}': No such file or directory\nExecution halted\n")
  ess-r--flymake-check-errors()
  ess-r--flymake-parse-output(#<buffer  *ess-r-flymake*> #<buffer dummy.R> #f(compiled-function (&rest args) #<bytecode 0x45e4a775>))
  #f(compiled-function (proc event) #<bytecode 0x4307fddd>)(#<process ess-r-flymake> "exited abnormally with code 1\n")

It looks like the whole function is interpreted as a filename. Is this a bug in ESS? It seems unlikely, as this error is annoying enough that others would have reported it. Any idea on how to investigate this further?