hardened json parsing + updated tests

Author: ajungg

core/src/androidTest/assets/demoDb_1_11.sqlite3

@@ -10,5 +10,10 @@
   "eans": [
     "0"
   ],
+  "codes": [
+    {
+      "code": "0"
+    }
+  ],
   "productType": "default"
 }

core/src/androidTest/assets/product.json

@@ -388,4 +388,16 @@ public void testTransmissionCodeIsSameOnOldDbVersion() throws IOException, Snabb
 
         Assert.assertEquals(product.getTransmissionCode(product.getScannableCodes()[0]), product.getScannableCodes()[0]);
     }
+
+
+    @Test
+    public void testTransmissionCode() throws IOException, Snabble.SnabbleException {
+        setupSdkWithDb("demoDb_1_11.sqlite3");
+
+        ProductDatabase productDatabase = project.getProductDatabase();
+        Product product = productDatabase.findBySku("48");
+        Assert.assertNotNull(product);
+
+        Assert.assertEquals(product.getTransmissionCode(product.getScannableCodes()[0]), "00000" + product.getScannableCodes()[0]);
+    }
  }

core/src/androidTest/java/io/snabble/sdk/ProductDatabaseTest.java

@@ -385,7 +385,9 @@ private Product toProduct(ApiProduct apiProduct, Product depositProduct, Product
 
         if(apiProduct.codes != null) {
             for (ApiScannableCode apiScannableCode : apiProduct.codes) {
-                builder.addTransmissionCode(apiScannableCode.code, apiScannableCode.transmissionCode);
+                if(apiScannableCode.code != null && apiScannableCode.transmissionCode != null) {
+                    builder.addTransmissionCode(apiScannableCode.code, apiScannableCode.transmissionCode);
+                }
             }
         }