fix: check if log directory exists before writing logs (#17)

Previously, if we found the user's workspace, we would just assume that
the `.trunk/logs` directory exists. This PR adds a check for the
directory. If it does not exist, we write logs to a temp file instead.

Fixes #16.

lua/log.lua

@@ -25,6 +25,15 @@ local function findWorkspace()
 	return vim.fs.dirname(vim.fs.find({ ".trunk", ".git" }, { upward = true })[1])
 end
 
+local function getOutFile()
+	local log_dir = findWorkspace() and findWorkspace() .. "/.trunk/logs"
+	if log_dir and vim.fn.isdirectory(log_dir) ~= 0 then
+		return log_dir .. "/neovim.log"
+	else
+		return os.tmpname()
+	end
+end
+
 -- User configuration section
 local default_config = {
 	-- Name of the plugin. Prepended to log messages
@@ -40,7 +49,7 @@ local default_config = {
 	use_file = true,
 
 	-- Default file to write
-	out_file = findWorkspace() and findWorkspace() .. "/.trunk/logs/neovim.log" or os.tmpname(),
+	out_file = getOutFile(),
 
 	-- Any messages above this level will be logged.
 	level = "info",