fix: don't fail if some unhandled error occurs in application

[Fatme]

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• You have signed the CLA.
• All existing tests are passing: https://github.com/NativeScript/nativescript-cli/blob/master/CONTRIBUTING.md#contribute-to-the-code-base
• Tests for the changes are included.

What is the current behavior?

If some error is thrown from application, {N} CLI stops command execution

What is the new behavior?

If some error is thrown from application, {N} CLI does not stop command execution

Steps to reproduce:

1. Run tns preview command
2. Scan QR code
3. Throw some error from application

[Fatme]

run ci