Is it possible for sshkit capture to not error when the command executed returns nothing - capistrano3

Question

What I'm trying to achieve is a capistrano3 task that does a log file grep on all servers - this would save a lot of time as we have a lot of servers so doing it manually or even scripted but sequentially takes ages.
I have a rough at the edges task that actually works except when one of the servers returns nothing for the grep. In this case the whole command falls over.
Hence wondering if there is a way to set capture to accept empty returns.
namespace :admin do
task :log_grep, :command, :file do |t,args|
command = args[:command] || 'ask for a command'
file = args[:file] || 'log_grep_results'
outs = {}
on roles(:app), in: :parallel do
outs[host.hostname] = capture(:zgrep, "#{command}")
end
File.open(file, 'w') do |fh|
outs.each do |host,out|
fh.write(out)
end
end
end
end

Answer 1

Should anyone else come to this question, here's solution - raise_on_non_zero_exit: false
i wanted:
resp = capture %([ -f /var/run/xxx/xxx.pid ] && echo "ok")
error:
SSHKit::Command::Failed: [ -f /var/run/xxx/xxx.pid ] && echo "ok" exit status: 1
[ -f /var/run/xxx/xxx.pid ] && echo "ok" stdout: Nothing written
[ -f /var/run/xxx/xxx.pid ] && echo "ok" stderr: Nothing written
solution:
resp = capture %([ -f /var/run/xxx/xxx.pid ] && echo "ok"), raise_on_non_zero_exit: false
# resp => ""

Answer 2

So the work around I did was to start adding what I'm calling Capistrano utility scripts in the repo. Then capistrano runs these scripts. All the scripts are is a wrapper around a grep and some logic to output something if the return is empty.
Capistrano code:
namespace :utils do
task :log_grep, :str, :file, :save_to do |t,args|
command_args = "#{args[:str]} #{args[:file]}"
outs = {}
on roles(:app), in: :parallel do
outs[host.hostname] = capture(:ruby, "#{fetch(:deploy_to)}/current/bin/log_grep.rb #{args[:str]} #{args[:file]}")
end
file = args[:save_to]
file ||= 'log_grep_output'
File.open(file, 'w') do |fh|
outs.each do |host,out|
s = "#{host} -- #{out}\n"
fh.write(s)
end
end
end
end
Ruby script log_grep.rb:
a = `zgrep #{ARGV[0]} #{ARGV[1]}`
if a.empty?
puts 'Nothing Found'
else
puts a
end