Fix find_upwards

- Use `util.vis_pipe` instead of `vis:pipe` as this does not work on the
  current release of vis.
- Quote the path to the find-upwards script. It resides in
  `~/Library/Application Support` on my macOS setup, and while not very
  common, paths in other users' configurations might have the same
  issue.
- At least during testing, `out` was nil in some cases. `find_upwards`
  checks it now.

1 files changed, 3 insertions, 2 deletions

diff --git a/util.lua b/util.lua
index de5ad07..a8ca1be 100644
--- a/util.lua
+++ b/util.lua
@@ -195,9 +195,10 @@ end
 -- @param globs a new line separated string of file globs
 -- @param start the starting path
 function util.find_upwards(globs, start)
-  local status, out = vis:pipe(globs, source_path .. '/tools/find-upwards "' .. start .. '"')
+  local status, out = util.vis_pipe(globs, '\'' .. source_path:gsub('\'', '\'\\\'\'') ..
+                                        '/tools/find-upwards\' "' .. start .. '"')
 
-  if status ~= 0 then
+  if status ~= 0 or out == nil then
     return nil
   end