fixed issue #47; flag-style tags like @local were blowing up with description collection

ldoc/doc.lua

@@ -379,7 +379,9 @@ function Item:_init(tags,file,line)
 end
 
 function Item:add_to_description (rest)
-   self.description = (self.description or '') .. rest
+   if type(rest) == 'string' then
+      self.description = (self.description or '') .. rest
+   end
 end
 
 function Item:set_tag (tag,value)

tests/usage/usage.lua

@@ -6,6 +6,13 @@ A simple module with examples.
 
 local usage = {}
 
+local helper
+
+--- a local helper function.
+-- @local
+function helper ()
+end
+
 ----------
 -- A simple vector class.
 --
@@ -18,6 +25,7 @@ local usage = {}
 local Vector = {}
 usage.Vector = {}
 
+
 ----------
 -- Create a vector from an array `t`.
 -- `Vector` is also callable!