Terminal tooltip error

[robertjk]

I'm using Neovim (0.4.2) in terminal and I enabled "tooltip" support as per README recommendation:

autocmd FileType typescript nmap <buffer> <Leader>t : <C-u>echo tsuquyomi#hint()<CR>

Whenever I press <Leader>t I get the following error:

Error detected while processing function tsuquyomi#hint[2]..tsuquyomi#tsClient#tsQuickinfo[2]..tsuquyomi#tsClient#sendCommandSyncResponse[3]..tsuquyomi#tsClient#sendRequest[2]..tsuquyomi#tsClient#startTss[2]..<SNR>122_startTssVimproc[5]..<SNR>114_touch:
line    4:
E117: Unknown function: vimproc#popen3
E15: Invalid expression: vimproc#popen3(a:cmd)
Error detected while processing function tsuquyomi#hint[2]..tsuquyomi#tsClient#tsQuickinfo[2]..tsuquyomi#tsClient#sendCommandSyncResponse[3]..tsuquyomi#tsClient#sendRequest[4]..<SNR>114_writeln[1]..<SNR>114_write:
line    2:
E605: Exception not caught: vital: ProcessManager: doesn't know about tsuquyomiTSServer
Error detected while processing function tsuquyomi#hint[2]..tsuquyomi#tsClient#tsQuickinfo[2]..tsuquyomi#tsClient#sendCommandSyncResponse[3]..tsuquyomi#tsClient#sendRequest:
line    4:
E171: Missing :endif