PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[X] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Currently, when using DialogModule.forRoot() without any parameters, the dialog pops pup but can't close, it get the following error message:

ERROR TypeError: Cannot read property 'onClose' of undefined

You can find a repro here. When adding an empty object to forRoot(), it works as expected.

Issue Number: N/A

What is the new behavior?

This patch adds a default empty object.

Does this PR introduce a breaking change?

[ ] Yes
[X] No

Other information