check the plugin return code is 0
if not print all outputs from plugin and exit 1

refactor testing to detect broken plugins
add list-all command to testing
refactor 2 list tests to include broken plugin
split some test asertions to aid readability

update dummy plugin to include error to ignore
update broken plugin to add stderr output
update list-all test to check for stderr on failure
update list-all test to check for no stderr on success