Vim-rspec tmux errror

Having a weird issue when I run vim-rspec commands. Sometimes I get an error like:

Error detected while processing function RunNearestSpec..<SNR>52_RunSpecs..Send_to_Tmux..<SNR>19_tmux_target:
line    1:
E716: Key not present in Dictionary: window
E15: Invalid expression: '"' . g:tslime['session'] . '":' . g:tslime['window'] . "." . g:tslime['pane']

Any direction on what to look at with this?

Ah realized it asks for session name. I guess I have to give it the first time if I have multiple tmux sessions open?