patch 8.2.2545: errors and crash when terminal window is zero height

Problem:    Errors and crash when terminal window is zero height. (Leonid V.
            Fedorenchik)
Solution:   Do not resize when width or height is zero. (closes #7890)
diff --git a/src/terminal.c b/src/terminal.c
index 9729eac..4c43ea7 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -3800,6 +3800,11 @@
     newrows = rows == 0 ? newrows : minsize ? MAX(rows, newrows) : rows;
     newcols = cols == 0 ? newcols : minsize ? MAX(cols, newcols) : cols;
 
+    // If no cell is visible there is no point in resizing.  Also, vterm can't
+    // handle a zero height.
+    if (newrows == 0 || newcols == 0)
+	return;
+
     if (term->tl_rows != newrows || term->tl_cols != newcols)
     {
 	term->tl_vterm_size_changed = TRUE;