[fix] Ensure "Open last/previous" point to existing files (#4367)

frontend/apps/filemanager/filemanager.lua

@@ -228,6 +228,7 @@ function FileManager:init()
                             ok_callback = function()
                                 deleteFile(file)
                                 filemanagerutil.removeFileFromHistoryIfWanted(file)
+                                filemanagerutil.ensureLastFileExists()
                                 self:refreshPath()
                                 UIManager:close(self.file_dialog)
                             end,

frontend/apps/filemanager/filemanagerhistory.lua

@@ -87,6 +87,7 @@ function FileManagerHistory:onMenuHold(item)
                             FileManager:deleteFile(item.file)
                             filemanagerutil.removeFileFromHistoryIfWanted(item.file)
                             require("readhistory"):setDeleted(item)
+                            filemanagerutil.ensureLastFileExists()
                             self._manager:updateItemTable()
                             UIManager:close(self.histfile_dialog)
                         end,

frontend/apps/filemanager/filemanagerutil.lua

@@ -50,16 +50,28 @@ function filemanagerutil.purgeSettings(file)
     end
 end
 
--- Remove from history and update lastfile to top item in history
+-- Remove from history (and update lastfile to an existing file)
 -- if autoremove_deleted_items_from_history is enabled
 function filemanagerutil.removeFileFromHistoryIfWanted(file)
     if G_reader_settings:readSetting("autoremove_deleted_items_from_history") then
         local readhistory = require("readhistory")
         readhistory:removeItemByPath(file)
-        if G_reader_settings:readSetting("lastfile") == file then
-            G_reader_settings:saveSetting("lastfile", #readhistory.hist > 0 and readhistory.hist[1].file or nil)
+        filemanagerutil.ensureLastFileExists()
+    end
+end
+
+-- Update lastfile setting to the most recent one in history
+-- that still exists
+function filemanagerutil.ensureLastFileExists()
+    local last_existing_file = nil
+    local readhistory = require("readhistory")
+    for i=1, #readhistory.hist do
+        if lfs.attributes(readhistory.hist[i].file, "mode") == "file" then
+            last_existing_file = readhistory.hist[i].file
+            break
         end
     end
+    G_reader_settings:saveSetting("lastfile", last_existing_file)
 end
 
 return filemanagerutil

frontend/apps/reader/modules/readermenu.lua

@@ -186,29 +186,35 @@ function ReaderMenu:setUpdateItemTable()
         end,
     }
 
-    local previous_file
-    local readhistory = require("readhistory")
-    for i=2, #readhistory.hist do -- skip first one which is current book
-        if lfs.attributes(readhistory.hist[i].file, "mode") == "file" then
-            previous_file = readhistory.hist[i].file
-            break
+    local getPreviousFile = function()
+        local previous_file = nil
+        local readhistory = require("readhistory")
+        for i=2, #readhistory.hist do -- skip first one which is current book
+            -- skip deleted items kept in history
+            if lfs.attributes(readhistory.hist[i].file, "mode") == "file" then
+                previous_file = readhistory.hist[i].file
+                break
+            end
         end
+        return previous_file
     end
     self.menu_items.open_previous_document = {
         text_func = function()
+            local previous_file = getPreviousFile()
             if not G_reader_settings:isTrue("open_last_menu_show_filename") or not previous_file then
                 return _("Open previous document")
             end
-            local path, file_name = util.splitFilePathName(previous_file); -- luacheck: no unused
+            local path, file_name = util.splitFilePathName(previous_file) -- luacheck: no unused
             return T(_("Previous: %1"), file_name)
         end,
         enabled_func = function()
-            return previous_file ~= nil
+            return getPreviousFile() ~= nil
         end,
         callback = function()
-            self.ui:switchDocument(previous_file)
+            self.ui:switchDocument(getPreviousFile())
         end,
         hold_callback = function()
+            local previous_file = getPreviousFile()
             UIManager:show(ConfirmBox:new{
                 text = T(_("Would you like to open the previous document: %1?"), previous_file),
                 ok_text = _("OK"),