Fix crash on startup when terminal doesnt support colors

rtv/objects.py

@@ -83,6 +83,7 @@ def curses_session():
         # return from C start_color() is ignorable.
         try:
             curses.start_color()
+            curses.use_default_colors()
         except:
             _logger.warning('Curses failed to initialize color support')
 
@@ -92,9 +93,6 @@ def curses_session():
         except:
             _logger.warning('Curses failed to initialize the cursor mode')
 
-        # Assign the terminal's default (background) color to code -1
-        curses.use_default_colors()
-
         yield stdscr
 
     finally:

rtv/terminal.py

@@ -849,7 +849,7 @@ class Terminal(object):
         """
         monochrome = (not curses.has_colors())
 
-        if theme is None:
+        if theme is None or monochrome:
             theme = Theme(monochrome=monochrome)
 
         theme.bind_curses()

tests/test_terminal.py

@@ -596,3 +596,16 @@ def test_set_theme(terminal, stdscr):
     terminal.set_theme(theme=theme)
     assert terminal.theme.monochrome
     stdscr.bkgd.assert_called_once_with(' ', 0)
+
+
+def test_set_theme_no_colors(terminal, stdscr):
+
+    with mock.patch('curses.has_colors') as has_colors:
+        has_colors.return_value = False
+
+        terminal.set_theme()
+        assert terminal.theme.monochrome
+
+        theme = Theme(monochrome=False)
+        terminal.set_theme(theme=theme)
+        assert terminal.theme.monochrome