Details of an error which happens when attempting to complete in a cider repl using tab

doom-info.txt

emacs   version    28.0.50
        features   JPEG TIFF PNG NOTIFY KQUEUE ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES THREADS PDUMPER
        build      Aug 17, 2020
        buildopts  (--with-mailutils --prefix=/usr/local/emacs-git --disable-ns-self-contained)
        windowsys  ns
        daemonp    server-running
doom    version    2.0.9
        build      HEAD -> develop 58af4aef5 2020-08-18 02:51:53 -0400
        dir        ~/.doom.d/
system  type       darwin
        config     x86_64-apple-darwin19.6.0
        shell      /bin/zsh
        uname      Darwin 19.6.0 Darwin Kernel Version 19.6.0: Sun Jul  5 00:43:10 PDT 2020; root:xnu-6153.141.1~9/RELEASE_X86_64 x86_64
        path       (~/Scratch/go/bin /usr/local/bin /usr/bin /bin /usr/sbin /sbin /Applications/VMware Fusion.app/Contents/Public /Library/Java/JavaVirtualMachines/graalvm-ce-java11-20.1.0/Contents/Home/bin ~/.local/share/ponyup/bin /usr/local/CrossPack-AVR/bin ~/scratch/emacs/doom-emacs/bin /usr/local/emacs-git/bin /usr/local/opt/texinfo/bin /usr/local/opt/coreutils/libexec/gnubin /usr/local/sbin ~/bin ~/.cargo/bin ~/Scratch/go/bin /usr/local/anaconda3/bin /usr/local/anaconda3/condabin /usr/local/emacs-git/libexec/emacs/28.0.50/x86_64-apple-darwin19.6.0/)
config  envfile    envvar-file
        elc-files  91
        modules    (:completion (company +tng) (ivy +prescient) :ui deft doom hl-todo hydra modeline nav-flash ophints (popup +defaults) treemacs unicode vc-gutter vi-tilde-fringe window-select workspaces :editor (evil +everywhere) fold format word-wrap :emacs dired electric ibuffer undo vc :term vterm :checkers syntax :tools docker (eval +overlay) gist (lookup +dictionary) lsp magit terraform :lang clojure common-lisp data emacs-lisp (go +lsp) (haskell +dante) idris json (java +meghanada) javascript kotlin lua markdown ocaml org purescript (python +lsp +conda) racket rest rst (ruby +rails) (rust +lsp) scheme sh web yaml :email (mu4e +gmail) :app calendar irc twitter :config (default +bindings +smartparens))
        packages   ((dracula-theme) (paredit) (evil-paredit))
        unpin      (n/a)
        elpa       (n/a)

emacs error trace

Debugger entered--Lisp error: (error "Lisp nesting exceeds ‘max-lisp-eval-depth’")
  key-binding([tab])
  company--should-complete()
  company--perform()
  company-auto-begin()
  company-manual-begin()
  (and (company-manual-begin) (= company-candidates-length 1))
  +company-has-completion-p()
  (and (featurep! :completion company +tng) (+company-has-completion-p))
  (cond ((and (featurep! :editor snippets) (bound-and-true-p yas-minor-mode) (yas-maybe-expand-abbrev-key-filter 'yas-expand)) #'yas-expand) ((and (featurep! :completion company +tng) (+company-has-completion-p)) #'+company/complete) (t nil))
  (lambda (&optional _) (cond ((and (featurep! :editor snippets) (bound-and-true-p yas-minor-mode) (yas-maybe-expand-abbrev-key-filter 'yas-expand)) #'yas-expand) ((and (featurep! :completion company +tng) (+company-has-completion-p)) #'+company/complete) (t nil)))(nil)
  key-binding([tab])
  company--should-complete()
  company--perform()
  company-auto-begin()
  company-manual-begin()
  (and (company-manual-begin) (= company-candidates-length 1))
  +company-has-completion-p()
  (and (featurep! :completion company +tng) (+company-has-completion-p))
  (cond ((and (featurep! :editor snippets) (bound-and-true-p yas-minor-mode) (yas-maybe-expand-abbrev-key-filter 'yas-expand)) #'yas-expand) ((and (featurep! :completion company +tng) (+company-has-completion-p)) #'+company/complete) (t nil))
  (lambda (&optional _) (cond ((and (featurep! :editor snippets) (bound-and-true-p yas-minor-mode) (yas-maybe-expand-abbrev-key-filter 'yas-expand)) #'yas-expand) ((and (featurep! :completion company +tng) (+company-has-completion-p)) #'+company/complete) (t nil)))(nil)
  key-binding([tab])

Note that the error trace is much longer, but just repeats over and over, which indeed seems to be the problem.

Ah so, I tracked this down to this code and was able to fix it by removing +tng from my company module setup.