Fix #370 - Panic when trying to set colors when colors are disabled

src/options.go

@@ -380,8 +380,11 @@ func parseTiebreak(str string) tiebreak {
 }
 
 func dupeTheme(theme *curses.ColorTheme) *curses.ColorTheme {
-	dupe := *theme
-	return &dupe
+	if theme != nil {
+		dupe := *theme
+		return &dupe
+	}
+	return nil
 }
 
 func parseTheme(defaultTheme *curses.ColorTheme, str string) *curses.ColorTheme {
@@ -402,7 +405,7 @@ func parseTheme(defaultTheme *curses.ColorTheme, str string) *curses.ColorTheme
 			}
 			// Color is disabled
 			if theme == nil {
-				errorExit("colors disabled; cannot customize colors")
+				continue
 			}
 
 			pair := strings.Split(str, ":")

src/options_test.go

@@ -316,3 +316,15 @@ func TestColorSpec(t *testing.T) {
 		t.Errorf("using default colors")
 	}
 }
+
+func TestParseNilTheme(t *testing.T) {
+	var theme *curses.ColorTheme
+	newTheme := parseTheme(theme, "prompt:12")
+	if newTheme != nil {
+		t.Errorf("color is disabled. keep it that way.")
+	}
+	newTheme = parseTheme(theme, "prompt:12,dark,prompt:13")
+	if newTheme.Prompt != 13 {
+		t.Errorf("color should now be enabled and customized")
+	}
+}