Lsp fails to start in spacemacs ESS(R) mode

Hi,

I am on spacemacs, so I am not sure whether this is an ESS issue or a spacemacs issue. In any case, I am trying to use the lsp server for R files but it fails to start (even after restarts. The lsp--r::stderr file reads:

[2021-07-05 09:22:04.206] error handling json:  Error: lexical error: invalid char in json text.
          = dplyr::lag(polls_diff_D_R{"jsonrpc":"2.0","method":"textDo
                     (right here) ------^

Stack trace:
1: parse_string(txt, bigint_as_char)
2: parseJSON(txt, bigint_as_char)
3: parse_and_simplify(txt = txt, simplifyVector = simplifyVector, 
    simplifyDataFrame = simplifyDataFrame, simplifyMatrix = simplifyMatrix, 
    flatten = flatten, ...)
4: jsonlite::fromJSON(data, simplifyVector = FALSE)
[2021-07-05 09:22:04.248] Error: Unexpected non-empty line
Call: self$read_header()
Stack trace:
1: stop("Unexpected non-empty line")
2: self$read_header()
3: self$fetch(blocking = FALSE)
[2021-07-05 09:22:04.248] exiting

Process lsp-r stderr finished

I tried installing the latest version of the language server as suggested here in issue 121).

Any help would greatly be appreciated.

The issue mentions lsp--r::stderr and ESS(R) mode; start by reproducing the failure in Spacemacs and inspect that stderr output alongside issue 121. Done means the R language server starts successfully and accepts the JSON/LSP input without the reported parse and header errors.