PgClient: NPE when inserting null param with default param extractor (#1486)

See #1477

This is a regression introduced in #1464

When the value is null, the extractor throws a failure.
Then, in ErrorMessageFactory.buildWhenArgumentsTypeNotMatched, a NPE is thrown because the value of the class cannot be determined.

Signed-off-by: Thomas Segismont <tsegismont@gmail.com>

Author: tsegismont

vertx-pg-client/src/main/java/io/vertx/pgclient/impl/codec/DataType.java

@@ -237,7 +237,10 @@ private static class DefaultParamExtractor<T> implements ParamExtractor<T> {
     @Override
     public T get(TupleInternal tuple, int idx) {
       Object value = tuple.getValue(idx);
-      if (value != null && encodingType.isAssignableFrom(value.getClass())) {
+      if (value == null) {
+        return null;
+      }
+      if (encodingType.isAssignableFrom(value.getClass())) {
         return encodingType.cast(value);
       }
       throw FAILURE;

vertx-pg-client/src/test/java/io/vertx/pgclient/data/PreparedStatementParamCoercionTest.java

@@ -1,9 +1,9 @@
 package io.vertx.pgclient.data;
 
-import io.vertx.pgclient.PgConnection;
-import io.vertx.sqlclient.Tuple;
 import io.vertx.ext.unit.Async;
 import io.vertx.ext.unit.TestContext;
+import io.vertx.pgclient.PgConnection;
+import io.vertx.sqlclient.Tuple;
 import io.vertx.sqlclient.data.Numeric;
 import org.junit.Test;
 
@@ -68,4 +68,16 @@ public void testCoercionError(TestContext ctx) {
       }));
     }));
   }
+
+  @Test
+  public void testNoCoercionErrorWithNull(TestContext ctx) {
+    PgConnection.connect(vertx, options).onComplete(ctx.asyncAssertSuccess(conn -> {
+      conn.prepare("SELECT $1::POINT").onComplete(ctx.asyncAssertSuccess(pq -> {
+        pq
+          .query()
+          .execute(Tuple.of(null))
+          .onComplete(ctx.asyncAssertSuccess());
+      }));
+    }));
+  }
 }