fix: Disallow nil passing to create_dirs()

To tackle deletion and creation path issues, commit 6e1fa15 ("feat:
Enable user to get "out" of a worktree") added the possibility of passing
nil to change_dirs(). But the problems can be solved in a better way:

When deleting, check if the selection is the current tree then change dir
to gitroot_dir() if so. When creating, add gitroot_dir() as prefix.

lua/git-worktree/worktree.lua

@@ -14,15 +14,6 @@ local function get_absolute_path(path)
 end
 
 local function change_dirs(path)
-    if path == nil then
-        local out = vim.fn.systemlist('git rev-parse --git-common-dir')
-        if vim.v.shell_error ~= 0 then
-            Log.error('Could not parse common dir')
-            return
-        end
-        path = out[1]
-    end
-
     Log.info('changing dirs:  %s ', path)
     local worktree_path = get_absolute_path(path)
     local previous_worktree = vim.loop.cwd()
@@ -72,24 +63,20 @@ local M = {}
 --Switch the current worktree
 ---@param path string?
 function M.switch(path)
-    if path == nil then
-        change_dirs(path)
-    else
-        if path == vim.loop.cwd() then
+    if path == vim.loop.cwd() then
+        return
+    end
+    Git.has_worktree(path, nil, function(found)
+        if not found then
+            Log.error('Worktree does not exists, please create it first %s ', path)
             return
         end
-        Git.has_worktree(path, nil, function(found)
-            if not found then
-                Log.error('Worktree does not exists, please create it first %s ', path)
-                return
-            end
 
-            vim.schedule(function()
-                local prev_path = change_dirs(path)
-                Hooks.emit(Hooks.type.SWITCH, path, prev_path)
-            end)
+        vim.schedule(function()
+            local prev_path = change_dirs(path)
+            Hooks.emit(Hooks.type.SWITCH, path, prev_path)
         end)
-    end
+    end)
 end
 
 --- CREATE ---

lua/telescope/_extensions/git_worktree.lua

@@ -18,9 +18,6 @@ local force_next_deletion = false
 -- @return string: the path of the selected worktree
 local get_worktree_path = function(prompt_bufnr)
     local selection = action_state.get_selected_entry(prompt_bufnr)
-    if selection == nil then
-        return
-    end
     return selection.path
 end
 
@@ -118,12 +115,14 @@ local delete_worktree = function(prompt_bufnr)
         return
     end
 
-    git_worktree.switch_worktree(nil)
-
-    local worktree_path = get_worktree_path(prompt_bufnr)
+    local selected = get_worktree_path(prompt_bufnr)
     actions.close(prompt_bufnr)
-    if worktree_path ~= nil then
-        git_worktree.delete_worktree(worktree_path, force_next_deletion, {
+    if selected ~= nil then
+        local current = vim.loop.cwd()
+        if current == selected then
+            git_worktree.switch_worktree(Git.gitroot_dir())
+        end
+        git_worktree.delete_worktree(selected, force_next_deletion, {
             on_failure = delete_failure_handler,
             on_success = delete_success_handler,
         })
@@ -137,8 +136,7 @@ local create_input_prompt = function(opts, cb)
     opts = opts or {}
     opts.pattern = nil -- show all branches that can be tracked
 
-    local prefix = opts.prefix or ''
-    local path = vim.fn.input('Path to subtree > ', prefix .. opts.branch)
+    local path = vim.fn.input('Path to subtree > ', Git.gitroot_dir() .. '/' .. opts.branch)
     if path == '' then
         Log.error('No worktree path provided')
         return
@@ -184,7 +182,6 @@ end
 -- @param opts table: the options for the telescope picker (optional)
 -- @return nil
 local telescope_create_worktree = function(opts)
-    git_worktree.switch_worktree(nil)
     opts = opts or {}
 
     local create_branch = function(prompt_bufnr, _)