Allow user to return nil from functions

README.md

@@ -134,12 +134,14 @@ require("global-note").open_note("food")
 local get_project_name = function()
   local project_directory, err = vim.loop.cwd()
   if project_directory == nil then
-    error(err)
+    vim.notify(err, vim.log.levels.WARN)
+    return nil
   end
 
   local project_name = vim.fs.basename(project_directory)
   if project_name == nil then
-    error("Unable to get the project name")
+    vim.notify("Unable to get the project name", vim.log.levels.WARN)
+    return nil
   end
 
   return project_name
@@ -161,14 +163,16 @@ local get_project_name = function()
   }):wait()
 
   if result.stderr ~= "" then
-    error(result.stderr)
+    vim.notify(result.stderr, vim.log.levels.WARN)
+    return nil
   end
 
   local project_directory = result.stdout:gsub("\n", "")
 
   local project_name = vim.fs.basename(project_directory)
   if project_name == nil then
-    error("Unable to get the project name")
+    vim.notify("Unable to get the project name", vim.log.levels.WARN)
+    return nil
   end
 
   return project_name

lua/global-note/init.lua

@@ -29,9 +29,9 @@ local M = {
 }
 
 ---@class GlobalNote_UserPreset
----@field filename? string|fun(): string Filename of the note.
----@field directory? string|fun(): string Directory to keep notes.
----@field title? string|fun(): string Floating window title.
+---@field filename? string|fun(): string? Filename of the note.
+---@field directory? string|fun(): string? Directory to keep notes.
+---@field title? string|fun(): string? Floating window title.
 ---@field command_name? string Ex command name.
 ---@field window_config? table|fun(): table A nvim_open_win config.
 ---@field post_open? fun() It's called after the window creation.

lua/global-note/preset.lua

@@ -1,9 +1,9 @@
 local utils = require("global-note.utils")
 
 ---@class GlobalNote_PresetOptions
----@field filename string|fun(): string Filename of the note.
----@field directory string|fun(): string Directory to keep notes.
----@field title string|fun(): string Floating window title.
+---@field filename string|fun(): string? Filename of the note.
+---@field directory string|fun(): string? Directory to keep notes.
+---@field title string|fun(): string? Floating window title.
 ---@field command_name? string Ex command name.
 ---@field window_config table|fun(): table A nvim_open_win config.
 ---@field post_open fun() It's called after the window creation.
@@ -72,19 +72,28 @@ local new = function(name, options)
   end
 
   ---Expands preset fields to a finite values.
-  ---@return GlobalNote_ExpandedPreset
+  ---If user can't produce a critical value then nil is returned.
+  ---@return GlobalNote_ExpandedPreset?
   function p:_expand_options()
     local filename = self.filename
     if type(filename) == "function" then
+      ---@diagnostic disable-next-line: cast-local-type
       filename = filename()
+      if filename == nil then
+        return
+      end
       if type(filename) ~= "string" or filename == "" then
         error("Filename function should return a non empty string")
       end
     end
 
     local directory = self.directory
     if type(directory) == "function" then
+      ---@diagnostic disable-next-line: cast-local-type
       directory = directory()
+      if directory == nil then
+        return
+      end
       if type(directory) ~= "string" or directory == "" then
         error("Directory function should return a non empty string")
       end
@@ -101,6 +110,7 @@ local new = function(name, options)
 
     local title = self.title
     if type(title) == "function" then
+      ---@diagnostic disable-next-line: cast-local-type
       title = title()
       if type(title) ~= "string" and title ~= nil then
         error("Title function should return a string or a nil")
@@ -155,6 +165,9 @@ local new = function(name, options)
   ---Opens the preset in a floating window
   function p:open()
     local expanded_preset = self:_expand_options()
+    if expanded_preset == nil then
+      return
+    end
     self:_open_in_float_window(expanded_preset)
   end