Fixed minor NPE warnings (#193)

Author: alex268

jooq-dialect/src/main/java/org/jooq/impl/FieldMapsForUpsertReplace.java

@@ -12,13 +12,15 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.stream.IntStream;
+
 import org.jooq.Context;
 import org.jooq.DataType;
 import org.jooq.Field;
 import org.jooq.Record;
 import org.jooq.RenderContext.CastMode;
 import org.jooq.Select;
 import org.jooq.Table;
+
 import static org.jooq.impl.Keywords.K_VALUES;
 import static org.jooq.impl.Tools.BooleanDataKey.DATA_STORE_ASSIGNMENT;
 
@@ -78,10 +80,9 @@ public Select<Record> upsertSelect() {
         Map<Field<?>, List<Field<?>>> v = valuesFlattened();
 
         return IntStream.range(0, rows)
-                .mapToObj(row -> (Select<Record>) DSL.select(Tools.map(v.entrySet(),
-                        e -> patchDefault0(e.getValue().get(row), e.getKey()))))
+                .mapToObj(row -> (Select<Record>) DSL.select(Tools.map(v.entrySet(), e -> patchDefault0(e.getValue().get(row), e.getKey()))))
                 .reduce(Select::unionAll)
-                .orElse(null);
+                .orElseThrow();
     }
 
     private void toSQL92Values(Context<?> ctx) {

jooq-dialect/src/main/java/tech/ydb/jooq/codegen/YdbIndexDefinition.java

@@ -1,16 +1,17 @@
 package tech.ydb.jooq.codegen;
 
+import java.util.ArrayList;
+import java.util.List;
+
 import org.jooq.SortOrder;
 import org.jooq.meta.AbstractIndexDefinition;
 import org.jooq.meta.ColumnDefinition;
 import org.jooq.meta.DefaultIndexColumnDefinition;
 import org.jooq.meta.IndexColumnDefinition;
 import org.jooq.meta.SchemaDefinition;
 import org.jooq.meta.TableDefinition;
-import tech.ydb.table.description.TableIndex;
 
-import java.util.ArrayList;
-import java.util.List;
+import tech.ydb.table.description.TableIndex;
 
 public class YdbIndexDefinition extends AbstractIndexDefinition {
     private final TableIndex tableIndex;
@@ -29,6 +30,9 @@ protected List<IndexColumnDefinition> getIndexColumns0() {
 
         for (String column : columns) {
             ColumnDefinition columnDefinition = getTable().getColumn(column);
+            if (columnDefinition == null) {
+                continue;
+            }
 
             IndexColumnDefinition definition = new DefaultIndexColumnDefinition(
                     this,