Print error if library.index is not parsed. Update index only after successful parsing.

Author: cmaglie

arduino-core/src/cc/arduino/contributions/libraries/LibrariesIndexer.java

@@ -89,12 +89,16 @@ private void parseIndex(File file) throws IOException {
       mapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
       mapper.configure(DeserializationFeature.EAGER_DESERIALIZER_FETCH, true);
       mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
-      index = mapper.readValue(indexIn, LibrariesIndex.class);
+      LibrariesIndex newIndex = mapper.readValue(indexIn, LibrariesIndex.class);
 
-      index.getLibraries()
+      newIndex.getLibraries()
         .stream()
         .filter(library -> library.getCategory() == null || "".equals(library.getCategory()) || !Constants.LIBRARY_CATEGORIES.contains(library.getCategory()))
         .forEach(library -> library.setCategory("Uncategorized"));
+
+      index = newIndex;
+    } catch (Exception e) {
+      System.err.println("Error parsing library.index:" + e.getMessage());
     } finally {
       IOUtils.closeQuietly(indexIn);
     }