Do not try to send GOODBYE message when connection is broken

To avoid unnecessary "write after end" errors when connection has been
closed because of an error.

Author: lutovich

src/v1/internal/connection.js

@@ -387,9 +387,9 @@ export default class Connection {
       this._log.debug(`${this} closing`);
     }
 
-    if (this._protocol) {
-      // protocol has been initialized
-      // use it to notify the database about the upcoming close of the connection
+    if (this._protocol && this.isOpen()) {
+      // protocol has been initialized and this connection is healthy
+      // notify the database about the upcoming close of the connection
       this._protocol.prepareToClose(NO_OP_OBSERVER);
     }
 

test/internal/connection.test.js

@@ -367,6 +367,27 @@ describe('Connection', () => {
       }).catch(done.fail);
   });
 
+  it('should not prepare broken connection to close', done => {
+    connection = createConnection('bolt://localhost');
+
+    connection.connect('my-connection/9.9.9', basicAuthToken())
+      .then(() => {
+        expect(connection._protocol).toBeDefined();
+        expect(connection._protocol).not.toBeNull();
+
+        // make connection seem broken
+        connection._isBroken = true;
+        expect(connection.isOpen()).toBeFalsy();
+
+        connection._protocol.prepareToClose = () => {
+          throw new Error('Not supposed to be called');
+        };
+
+        connection.close(() => done());
+      })
+      .catch(error => done.fail(error));
+  });
+
   function packedHandshakeMessage() {
     const result = alloc(4);
     result.putInt32(0, 1);