Make z -i and z -I with no arguments be interactive.

[chrisant996]

This commit makes z -i and z -I go interactive even with no args.

Refer to #122 for context.

[skywind3000]

thx

[skywind3000]

crashed when using "z -I" and press CTRL+D to terminate fzf without choosing anything:

but z -I . works fine if you choose nothing in fzf.

[chrisant996]

crashed when using "z -I" and press CTRL+D to terminate fzf without choosing anything:

but z -I . works fine if you choose nothing in fzf.

That problem can only occur if _ZL_MATCH_MODE is set to something other than 0.
That's why I didn't encounter it -- I'm using the default value of _ZL_MATCH_MODE which is 0.

The fix is this:

diff --git a/z.lua b/z.lua
index 941c66e..171fdf4 100755
--- a/z.lua
+++ b/z.lua
@@ -1979,7 +1979,7 @@ function main(argv)
                        path = z_cd(args)
                        if path == nil and Z_MATCHMODE ~= 0 then
                                local last = args[#args]
-                               if os.path.isdir(last) then
+                               if last and os.path.isdir(last) then
                                        path = os.path.abspath(last)
                                        path = os.path.norm(path)
                                end

[chrisant996]

I've updated the topic branch and submitted another pull request.