fix batch bug addproduct mutation (#95)

src/datasources/product-api.ts

@@ -380,7 +380,8 @@ export class ProductAPI extends BaseSQLDataSource {
    * set a unique path, artNo is the productId with e infront.
    */
   async addProduct(name: string, batch: string): Promise<number> {
-    const path = batch ? batch + ' ' + name : name;
+    const fixedBatch = !!batch ? batch : '';
+    const path = batch ? fixedBatch + ' ' + name : name;
     const productPath = slug(path);
     const safePath = await this.getUniqueProductPath(productPath, null);
 
@@ -395,7 +396,7 @@ export class ProductAPI extends BaseSQLDataSource {
     const id = idres[0];
     this.updateProductField(id, 'artNo', `e${id}`);
     await this.updateProductField(id, 'name', name);
-    await this.updateProductField(id, 'batch', batch);
+    await this.updateProductField(id, 'batch', fixedBatch);
     return id;
   }