fix(utils): is_uri empty path (#2671)

lua/telescope/utils.lua

@@ -174,7 +174,7 @@ utils.is_path_hidden = function(opts, path_display)
 end
 
 utils.is_uri = function(filename)
-  local char = string.byte(filename, 1)
+  local char = string.byte(filename, 1) or 0
 
   -- is alpha?
   if char < 65 or (char > 90 and char < 97) or char > 122 then

lua/tests/automated/utils_spec.lua

@@ -27,6 +27,7 @@ describe("is_uri", function()
       "hello",
       "hello:",
       "123",
+      "",
     }
     for _, input in ipairs(inputs) do
       it(input, function()