Several behavior fix

[Vigilans]

Introduction

Old behavior:

• When quickpicking language, if click other areas to cancel the selection, an undefined default language query will pop out:
  
• Sometimes, the leetcode-cli may print useful data, but exit with error code. In this case, an exception will be thrown, and useful data will not be passed.
• When submitting a solution, leetcode-cli may print Runtime error and exit with error code. With aforementioned behavior, an exception will be thrown, and result WebView cannot be shown.
  

New behavior:

• Perform extra check before default language query.
• When exiting with error code, collect the result data into the error object.
• When showing result provider, if there is any result data in the caught error object, extract it out to build the WebView. Otherwise, re-throw the error object.

[jdneo]

These are very good improvements for the extension.

@Vigilans Would you mind to create the issues for those bugs separately and link them to the PR here? Then I can cover these issues into the changelog.

[jdneo]

We can also add ignoreFocusOut: true into the showQuickPick()'s option to avoid user close the drop list by mistake

[Vigilans]

Tracked in the issues #236 and #237 .