Catch exception from RecordDecoder and fail the DNS query

When no decoder is found for a record type, RecordDecoder now throws DecoderException
instead of IllegalStateException.

The DnsClientImpl then catches this exception and fails the query, as
otherwise the handler is never called.

src/main/java/io/vertx/core/dns/impl/DnsClientImpl.java

@@ -14,6 +14,7 @@
 import io.netty.channel.*;
 import io.netty.channel.socket.DatagramChannel;
 import io.netty.channel.socket.InternetProtocolFamily;
+import io.netty.handler.codec.DecoderException;
 import io.netty.handler.codec.dns.*;
 import io.netty.handler.logging.LoggingHandler;
 import io.netty.util.collection.LongObjectHashMap;
@@ -261,7 +262,14 @@ void handle(DnsResponse msg) {
         List<T> records = new ArrayList<>(count);
         for (int idx = 0;idx < count;idx++) {
           DnsRecord a = msg.recordAt(DnsSection.ANSWER, idx);
-          T record = RecordDecoder.decode(a);
+          T record;
+          try {
+            record = RecordDecoder.decode(a);
+          } catch (DecoderException e) {
+            fail(e);
+            return;
+          }
+
           if (isRequestedType(a.type(), types)) {
             records.add(record);
           }

src/main/java/io/vertx/core/dns/impl/decoder/RecordDecoder.java

@@ -222,7 +222,7 @@ public static <T> T decode(DnsRecord record) {
         DnsRecordType type = record.type();
         Function<DnsRecord, ?> decoder = decoders.get(type);
         if (decoder == null) {
-            throw new IllegalStateException("Unsupported resource record type [id: " + type + "].");
+            throw new DecoderException("DNS record decoding error occurred: Unsupported resource record type [id: " + type + "].");
         }
         T result = null;
         try {