Do not reschedule a deleted scheduler item

schedule.remove from the scheduled command deletes the item.

src/command_download.cc

@@ -431,6 +431,9 @@ p_call_target(const torrent::Object::list_type& args) {
   const std::string& peer_id = itr++->as_string();
   const std::string& command_key = itr++->as_string();
 
+  if (download == nullptr)
+    throw torrent::input_error("invalid parameters: info-hash not found");
+
   torrent::HashString hash;
 
   if (peer_id.size() != 40)

src/core/view.cc

@@ -216,7 +216,7 @@ View::set_not_visible(Download* download) {
 
 void
 View::next_focus(unsigned int i) {
-  if (empty())
+  if (empty_visible())
     return;
 
   // If at the boundary, roll over
@@ -239,7 +239,7 @@ View::next_focus(unsigned int i) {
 
 void
 View::prev_focus(unsigned int i) {
-  if (empty())
+  if (empty_visible())
     return;
 
   // If at the boundary, roll over

src/display/window_file_list.cc

@@ -25,7 +25,10 @@ WindowFileList::WindowFileList(const ui::ElementFileList* element) :
 // Convert std::string to std::wstring of given width (in screen positions),
 // taking into account that some characters may be occupying two screen positions.
 std::wstring
-wstring_width(const std::string& i_str, [[maybe_unused]] int width) {
+wstring_width(const std::string& i_str, int width) {
+  if (width < 0)
+    width = 0;
+
   std::wstring result(width + 1, L' ');
   size_t length = std::mbstowcs(result.data(), i_str.c_str(), width);
 

src/rpc/command_scheduler.cc

@@ -61,14 +61,20 @@ CommandScheduler::call_item(value_type item) {
   // Remove the item before calling the command if it should be
   // removed.
 
+  std::string key = item->key();
+
   try {
     rpc::call_object(item->command());
 
   } catch (torrent::input_error& e) {
     if (m_slotErrorMessage)
-      m_slotErrorMessage("Scheduled command failed: " + item->key() + ": " + e.what());
+      m_slotErrorMessage("Scheduled command failed: " + key + ": " + e.what());
   }
 
+  // The command is allowed to erase or replace this item, which deletes it.
+  if (std::find(begin(), end(), item) == end())
+    return;
+
   // Still schedule if we caught a torrrent::input_error?
   auto next = item->next_time_scheduled();