FileManager: tell plugins to save settings on close (#5872)

So that Statistics settings modified while in FileManager
are saved.
Also allows resetting statistics when in FileManager
(where there is no current book id to exclude).

frontend/apps/filemanager/filemanager.lua

@@ -664,6 +664,7 @@ end
 
 function FileManager:onClose()
     logger.dbg("close filemanager")
+    self:handleEvent(Event:new("SaveSettings"))
     G_reader_settings:flush()
     UIManager:close(self)
     if self.onExit then

frontend/apps/reader/modules/readerdictionary.lua

@@ -972,9 +972,11 @@ function ReaderDictionary:onReadSettings(config)
 end
 
 function ReaderDictionary:onSaveSettings()
-    logger.dbg("save default dictionary", self.default_dictionary)
-    self.ui.doc_settings:saveSetting("default_dictionary", self.default_dictionary)
-    self.ui.doc_settings:saveSetting("disable_fuzzy_search", self.disable_fuzzy_search)
+    if self.ui.doc_settings then
+        logger.dbg("save default dictionary", self.default_dictionary)
+        self.ui.doc_settings:saveSetting("default_dictionary", self.default_dictionary)
+        self.ui.doc_settings:saveSetting("disable_fuzzy_search", self.disable_fuzzy_search)
+    end
 end
 
 function ReaderDictionary:toggleFuzzyDefault()

plugins/statistics.koplugin/main.lua

@@ -1808,6 +1808,9 @@ function ReaderStatistics:deleteBooksByTotalDuration(max_total_duration_mn)
                     max_total_duration_mn), max_total_duration_mn),
         ok_text = _("Remove"),
         ok_callback = function()
+            -- Allow following SQL statements to work even when doc less by
+            -- using -1 as the book id, as real book ids are positive.
+            local id_curr_book = self.id_curr_book or -1
             local conn = SQ3.open(db_location)
             local sql_stmt = [[
                     DELETE from page_stat
@@ -1816,13 +1819,13 @@ function ReaderStatistics:deleteBooksByTotalDuration(max_total_duration_mn)
                     )
                 ]]
             local stmt = conn:prepare(sql_stmt)
-            stmt:reset():bind(self.id_curr_book, max_total_duration_sec):step()
+            stmt:reset():bind(id_curr_book, max_total_duration_sec):step()
             sql_stmt = [[
                     DELETE from book
                     WHERE  id != ? and (total_read_time is NULL or total_read_time < ?)
                 ]]
             stmt = conn:prepare(sql_stmt)
-            stmt:reset():bind(self.id_curr_book, max_total_duration_sec):step()
+            stmt:reset():bind(id_curr_book, max_total_duration_sec):step()
             stmt:close()
             -- Get nb of deleted books
             sql_stmt = [[