Fixed NPE when setting Types field in core-libraries

The core libraries may come from platforms installed inside the
"sketchbook/hardware" directory. Those platforms are not indexed
and doesn't have a category field to propagate in the core-libraries.

Author: cmaglie

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

@@ -52,6 +52,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 
 import static processing.app.I18n.tr;
 
@@ -151,8 +152,11 @@ public void rescanLibraries() {
         .filter(l -> l.getTypes().contains("Contributed")) //
         .filter(l -> l.getLocation() == Location.CORE || l.getLocation() == Location.REFERENCED_CORE) //
         .forEach(l -> {
-          ContributedPlatform platform = BaseNoGui.indexer.getPlatformByFolder(l.getInstalledFolder());
-          l.setTypes(Collections.singletonList(platform.getCategory()));
+          File libFolder = l.getInstalledFolder();
+          Optional<ContributedPlatform> platform = BaseNoGui.indexer.getPlatformByFolder(libFolder);
+          if (platform.isPresent()) {
+            l.setTypes(Collections.singletonList(platform.get().getCategory()));
+          }
         });
   }
 

arduino-core/src/cc/arduino/contributions/packages/ContributionsIndexer.java

@@ -461,13 +461,11 @@ private List<ContributedPlatform> getInstalledPlatforms() {
     return index.getInstalledPlatforms();
   }
 
-  public ContributedPlatform getPlatformByFolder(final File folder) {
-    Optional<ContributedPlatform> platformOptional = getInstalledPlatforms().stream().filter(contributedPlatform -> {
+  public Optional<ContributedPlatform> getPlatformByFolder(final File folder) {
+    return getInstalledPlatforms().stream().filter(contributedPlatform -> {
       assert contributedPlatform.getInstalledFolder() != null;
       return FileUtils.isSubDirectory(contributedPlatform.getInstalledFolder(), folder);
     }).findFirst();
-
-    return platformOptional.orElse(null);
   }
 
   public ContributedPlatform getContributedPlaform(TargetPlatform targetPlatform) {