fetch: return errors instead of panicing

cmd/fetch/fetch.go

@@ -9,54 +9,54 @@ import (
 	"os"
 )
 
-func main() {
+func run() error {
 	var root []root
 
 	err := os.Mkdir("hoods", 0777)
 	if err != nil {
-		log.Panic(err)
+		return err
 	}
 
 	req, err := http.NewRequest(http.MethodGet, "https://keyserver.freifunk-franken.de/v2/hoods.php", nil)
 	if err != nil {
-		log.Panic(err)
+		return err
 	}
 
 	res, err := http.DefaultClient.Do(req)
 	if err != nil {
-		log.Panic(err)
+		return err
 	}
 
 	body, err := io.ReadAll(res.Body)
 	if err != nil {
-		log.Panic(err)
+		return err
 	}
 
 	err = json.Unmarshal(body, &root)
 	if err != nil {
-		log.Panic(err)
+		return err
 	}
 
 	for _, h := range root {
 		var hood Hood
 		req, err := http.NewRequest(http.MethodGet, fmt.Sprintf("https://keyserver.freifunk-franken.de/v2/?hoodid=%d", h.Id), nil)
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 
 		res, err := http.DefaultClient.Do(req)
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 
 		body, err := io.ReadAll(res.Body)
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 
 		err = json.Unmarshal(body, &hood)
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 
 		if len(h.Polygons) == 0 {
@@ -70,12 +70,19 @@ func main() {
 
 		b, err := json.MarshalIndent(hood, "", "    ")
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 
 		err = os.WriteFile("hoods/"+hood.HoodInfo.Name+".json", b, 0666)
 		if err != nil {
-			log.Panic(err)
+			return err
 		}
 	}
+	return nil
+}
+
+func main() {
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
 }