feat: exempt config/doctor from config errors, run doctor on failure

When the config file is malformed, config and doctor commands now
proceed with defaults (showing a warning). All other commands print
the parse error and automatically run doctor to aid diagnosis.

cmd/root.go

@@ -39,8 +39,14 @@ var rootCmd = &cobra.Command{
 
 func Execute() {
 	if configErr != nil {
-		printError(fmt.Errorf("cannot load config: %v", configErr))
-		os.Exit(1)
+		cmd, _, _ := rootCmd.Find(os.Args[1:])
+		if configSafeCmd(cmd) {
+			warnf("config error: %v (using defaults)", configErr)
+		} else {
+			printError(fmt.Errorf("cannot load config: %v", configErr))
+			runDoctor(os.Stderr)
+			os.Exit(1)
+		}
 	}
 	err := rootCmd.Execute()
 	if err != nil {
@@ -49,6 +55,16 @@ func Execute() {
 	}
 }
 
+// configSafeCmd reports whether cmd can run with a broken config.
+func configSafeCmd(cmd *cobra.Command) bool {
+	for c := cmd; c != nil; c = c.Parent() {
+		if c == configCmd || c == doctorCmd {
+			return true
+		}
+	}
+	return false
+}
+
 func init() {
 	rootCmd.AddGroup(&cobra.Group{ID: "keys", Title: "Key commands:"})