Fixed NPE in AbstractRowsEventDataDeserializer (shyiko#60)

Author: shyiko

src/main/java/com/github/shyiko/mysql/binlog/event/deserialization/AbstractRowsEventDataDeserializer.java

@@ -76,6 +76,11 @@ public AbstractRowsEventDataDeserializer(Map<Long, TableMapEventData> tableMapEv
     protected Serializable[] deserializeRow(long tableId, BitSet includedColumns, ByteArrayInputStream inputStream)
             throws IOException {
         TableMapEventData tableMapEvent = tableMapEventByTableId.get(tableId);
+        if (tableMapEvent == null) {
+            throw new MissingTableMapEventException("No TableMapEventData has been found for table id:" + tableId +
+                ". Usually that means that you have started reading binary log 'within the logic group'" +
+                " (e.g. from WRITE_ROWS and not proceeding TABLE_MAP");
+        }
         byte[] types = tableMapEvent.getColumnTypes();
         int[] metadata = tableMapEvent.getColumnMetadata();
         Serializable[] result = new Serializable[numberOfBitsSet(includedColumns)];

src/main/java/com/github/shyiko/mysql/binlog/event/deserialization/MissingTableMapEventException.java

@@ -0,0 +1,10 @@
+package com.github.shyiko.mysql.binlog.event.deserialization;
+
+import java.io.IOException;
+
+public class MissingTableMapEventException extends IOException {
+
+    public MissingTableMapEventException(String message) {
+        super(message);
+    }
+}