Keep a later config flag when extra words are present.

A non-flag word no longer stops parsing, and a missing home directory refuses to create or rewrite a config instead of writing an empty log path.

Co-authored-by: Cursor <cursoragent@cursor.com>

station/config.go

@@ -62,7 +62,11 @@ func loadConfig(path string) (loaded, error) {
 }
 
 func writeTemplate(path string) error {
-	body, err := jsonv2.Marshal(templateFile{LogFile: defaultLogPath()})
+	logFile, err := defaultLogPath()
+	if err != nil {
+		return err
+	}
+	body, err := jsonv2.Marshal(templateFile{LogFile: logFile})
 	if err != nil {
 		return err
 	}
@@ -99,7 +103,11 @@ func parseConfig(path string, body []byte) (loaded, error) {
 		if !operationalKindsOK(shape) {
 			return parseOperational(shape)
 		}
-		shape = withLogDefaults(shape)
+		var err error
+		shape, err = withLogDefaults(shape)
+		if err != nil {
+			return loaded{}, err
+		}
 		if err := rewriteConfig(path, shape); err != nil {
 			return loaded{}, fmt.Errorf("the file could not be read: %w", err)
 		}
@@ -189,12 +197,14 @@ func intField(name string, v jsontext.Value, min, max int) (int, error) {
 	return n, nil
 }
 
-func defaultLogPath() string {
-	home, err := os.UserHomeDir()
+var userHomeDir = os.UserHomeDir
+
+func defaultLogPath() (string, error) {
+	home, err := userHomeDir()
 	if err != nil {
-		return ""
+		return "", fmt.Errorf("config path: %w", err)
 	}
-	return filepath.Join(home, "funknetz.log")
+	return filepath.Join(home, "funknetz.log"), nil
 }
 
 func present(v jsontext.Value) bool { return len(v) > 0 }
@@ -243,7 +253,7 @@ func blockedLog(shape fileShape) (block bool, notice string) {
 	return true, ""
 }
 
-func withLogDefaults(shape fileShape) fileShape {
+func withLogDefaults(shape fileShape) (fileShape, error) {
 	shape.Host = rawOr(shape.Host, `""`)
 	shape.Port = rawOr(shape.Port, "0")
 	shape.Callsign = rawOr(shape.Callsign, `""`)
@@ -251,13 +261,17 @@ func withLogDefaults(shape fileShape) fileShape {
 	shape.TalkGroup = rawOr(shape.TalkGroup, "0")
 	shape.EnableLogging = rawOr(shape.EnableLogging, "false")
 	if !present(shape.LogFile) {
-		raw, err := jsonv2.Marshal(defaultLogPath())
+		logFile, err := defaultLogPath()
 		if err != nil {
-			raw = []byte(`""`)
+			return fileShape{}, err
+		}
+		raw, err := jsonv2.Marshal(logFile)
+		if err != nil {
+			return fileShape{}, err
 		}
 		shape.LogFile = jsontext.Value(raw)
 	}
-	return shape
+	return shape, nil
 }
 
 func rawOr(v jsontext.Value, fallback string) jsontext.Value {

station/home_test.go

@@ -0,0 +1,52 @@
+package station
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestMissingHomeDoesNotCreateConfig(t *testing.T) {
+	orig := userHomeDir
+	t.Cleanup(func() { userHomeDir = orig })
+	userHomeDir = func() (string, error) {
+		return "", errors.New("no home")
+	}
+
+	path := filepath.Join(t.TempDir(), "lab.json")
+	_, err := New(Options{ConfigPath: path})
+	if err == nil || !strings.HasPrefix(err.Error(), "config path:") {
+		t.Fatalf("New() error = %v, want a config path failure", err)
+	}
+	if _, statErr := os.Stat(path); !errors.Is(statErr, fs.ErrNotExist) {
+		t.Fatalf("stat = %v, want the file absent", statErr)
+	}
+}
+
+func TestMissingHomeDoesNotRewriteConfig(t *testing.T) {
+	orig := userHomeDir
+	t.Cleanup(func() { userHomeDir = orig })
+	userHomeDir = func() (string, error) {
+		return "", errors.New("no home")
+	}
+
+	path := filepath.Join(t.TempDir(), "lab.json")
+	original := []byte("{\"host\":\"127.0.0.1\",\"port\":5308,\"callsign\":\"DL1ABC\",\"authKey\":\"key\",\"talkGroup\":20}\n")
+	if err := os.WriteFile(path, original, 0o640); err != nil {
+		t.Fatal(err)
+	}
+	_, err := New(Options{ConfigPath: path})
+	if err == nil || !strings.HasPrefix(err.Error(), "config path:") {
+		t.Fatalf("New() error = %v, want a config path failure", err)
+	}
+	got, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(original) {
+		t.Fatalf("file = %q, want %q", got, original)
+	}
+}