plugin treeview: fix crash

When the max_project_files is set to a higher value than the allowed
system maximum file descriptors, and opening a project directory that
causes dirmonitor to open a watch on a lot of files or directories, at
least on MacOSX it causes all system.* file functions to return nil
(for too many opened files) which breaks the project files scan.

1 files changed, 22 insertions, 20 deletions

diff --git a/data/plugins/treeview.lua b/data/plugins/treeview.lua
index bdcb0f49..cc13ec59 100644
--- a/data/plugins/treeview.lua
+++ b/data/plugins/treeview.lua
@@ -153,28 +153,30 @@ function TreeView:each_item()
       count_lines = count_lines + 1
       y = y + h
       local i = 1
-      while i <= #dir.files and dir_cached.expanded do
-        local item = dir.files[i]
-        local cached = self:get_cached(dir, item, dir.name)
-
-        coroutine.yield(cached, ox, y, w, h)
-        count_lines = count_lines + 1
-        y = y + h
-        i = i + 1
-
-        if not cached.expanded then
-          if cached.skip then
-            i = cached.skip
-          else
-            local depth = cached.depth
-            while i <= #dir.files do
-              if get_depth(dir.files[i].filename) <= depth then break end
-              i = i + 1
+      if dir.files then -- if consumed max sys file descriptors this can be nil
+        while i <= #dir.files and dir_cached.expanded do
+          local item = dir.files[i]
+          local cached = self:get_cached(dir, item, dir.name)
+
+          coroutine.yield(cached, ox, y, w, h)
+          count_lines = count_lines + 1
+          y = y + h
+          i = i + 1
+
+          if not cached.expanded then
+            if cached.skip then
+              i = cached.skip
+            else
+              local depth = cached.depth
+              while i <= #dir.files do
+                if get_depth(dir.files[i].filename) <= depth then break end
+                i = i + 1
+              end
+              cached.skip = i
             end
-            cached.skip = i
           end
-        end
-      end -- while files
+        end -- while files
+      end
     end -- for directories
     self.count_lines = count_lines
   end)