[listview] fix a couple of glitches with the selection

src/db_sub_source.cc

@@ -52,7 +52,7 @@ db_label_source::text_value_for_line(textview_curses& tc,
      */
 
     label_out.clear();
-    if (row >= (int) this->dls_rows.size()) {
+    if (row < 0_vl || row >= (int) this->dls_rows.size()) {
         return;
     }
     for (int lpc = 0; lpc < (int) this->dls_rows[row].size(); lpc++) {
@@ -85,7 +85,7 @@ db_label_source::text_attrs_for_line(textview_curses& tc,
     struct line_range lr(0, 0);
     const struct line_range lr2(0, -1);
 
-    if (row >= (int) this->dls_rows.size()) {
+    if (row < 0_vl || row >= (int) this->dls_rows.size()) {
         return;
     }
     auto alt_row_index = row % 4;

src/hotkeys.cc

@@ -380,12 +380,14 @@ handle_paging_key(int ch)
 
         case 'J':
             if (tc->is_selectable()) {
-                tc->toggle_user_mark(&textview_curses::BM_USER,
-                                     tc->get_selection());
-                lnav_data.ld_select_start[tc] = tc->get_selection();
-                lnav_data.ld_last_user_mark[tc] = tc->get_selection();
-                if (tc->get_selection() + 1_vl < tc->get_inner_height()) {
-                    tc->set_selection(tc->get_selection() + 1_vl);
+                if (tc->get_selection() >= 0_vl) {
+                    tc->toggle_user_mark(&textview_curses::BM_USER,
+                                         tc->get_selection());
+                    lnav_data.ld_select_start[tc] = tc->get_selection();
+                    lnav_data.ld_last_user_mark[tc] = tc->get_selection();
+                    if (tc->get_selection() + 1_vl < tc->get_inner_height()) {
+                        tc->set_selection(tc->get_selection() + 1_vl);
+                    }
                 }
             } else {
                 if (lnav_data.ld_last_user_mark.find(tc)

src/listview_curses.cc

@@ -114,8 +114,11 @@ listview_curses::reload_data()
             } else if (this->lv_selection >= this->get_inner_height()) {
                 this->set_selection(this->get_inner_height() - 1_vl);
             } else {
-                auto curr_sel = this->lv_selection;
+                auto curr_sel = this->get_selection();
 
+                if (curr_sel == -1_vl) {
+                    curr_sel = 0_vl;
+                }
                 this->lv_selection = -1_vl;
                 this->set_selection(curr_sel);
             }

src/listview_curses.hh

@@ -236,7 +236,7 @@ public:
 
     vis_line_t get_selection() const
     {
-        if (this->lv_selectable) {
+        if (this->lv_selectable && this->lv_selection != -1_vl) {
             return this->lv_selection;
         }
         return this->lv_top;