SessionNotCreatedException throws when the Port is already in Use

The following error throws when the Port is not available.

```
session not created: This version of ChromeDriver only supports Chrome version 78
(Driver info: chromedriver=78.0.3904.70 (edb9c9f3de0247fd912a77b7f6cae7447f6d3ad5-refs/branch-heads/3904@{#800}),platform=Mac OS X 10.14.6 x86_64)
#0 parseJsonWireResponse (package:webdriver/src/handler/json_wire/utils.dart:79:9)
#1 JsonWireSessionHandler.parseInfoResponse (package:webdriver/src/handler/json_wire/session.dart:26:21)
#2 JsonWireSessionHandler.parseCreateResponse (package:webdriver/src/handler/json_wire/session.dart:18:7)
#3 AsyncRequestClient.send (package:webdriver/src/common/request_client.dart:96:25)

#4 createDriver (package:webdriver/async_core.dart:64:32)
#5 createDriver (package:webdriver/async_io.dart:42:5)
#6 _launchChrome (file:///Users/baradwav/Documents/dart-automation/main.dart:29:20)
```

It even defaults to chromeDriver=78.* and throws 'ChromeDriver only supports Chrome version 78' which is not a proper error message.

Checking the port with `netstat -vanp tcp | grep 4444` shows that the port is occupied.
Killing the Port manually solves the problem.

Shouldn't the package take care of this by itself? Kindly also provide a proper 'Error' message which is relevant to the issue.