Fix crashes in some enum operations

These are notable in the latest Android versions.

Author: rubengees

library/src/main/java/me/proxer/library/api/DelimitedEnumSetAdapterFactory.java

@@ -77,7 +77,9 @@ public Set<T> fromJson(final JsonReader reader) throws IOException {
 
             for (final String part : parts) {
                 for (final Field field : enumType.getFields()) {
-                    if (field.getAnnotation(Json.class).name().equals(part)) {
+                    Json annotation = field.getAnnotation(Json.class);
+
+                    if (annotation != null && annotation.name().equalsIgnoreCase(part)) {
                         result.add(Enum.valueOf(enumType, field.getName()));
 
                         break;

library/src/main/java/me/proxer/library/util/ProxerUtils.java

@@ -40,7 +40,9 @@ public String getApiEnumName(final Enum<?> it) {
     @Nullable
     public <T extends Enum<T>> T toApiEnum(final Class<T> type, final String value) {
         for (final Field field : type.getFields()) {
-            if (field.getAnnotation(Json.class).name().equalsIgnoreCase(value)) {
+            Json annotation = field.getAnnotation(Json.class);
+
+            if (annotation != null && annotation.name().equalsIgnoreCase(value)) {
                 return Enum.valueOf(type, field.getName());
             }
         }