Error when [showButtonBar]="true" is applied to the datepicker component

[lucas-mota-gomes]

Describe the bug

When enabling the [showButtonBar]="true" property on the datepicker component, the following error occurs:

ERROR Error: NgClass can only toggle CSS classes expressed as strings, got undefined at _NgClass._toggleClass (common.mjs:3012:15) at _NgClass._applyStateDiff (common.mjs:2996:14) at _NgClass.ngDoCheck (common.mjs:2973:10) at callHookInternal (core.mjs:4166:10) at callHook (core.mjs:4193:5) at callHooks (core.mjs:4150:9) at executeInitAndCheckHooks (core.mjs:4105:5) at selectIndexInternal (core.mjs:12624:9) at ɵɵadvance (core.mjs:12608:3) at DatePicker_div_3_div_6_Template (primeng-datepicker.mjs:1985:8)

Environment

Library Version: [v19.0.0]
Angular Version: [v19.0.3]

Additional Context:
If the [showButtonBar] property is set to false, the error does not occur.

Reproducer

No response

Angular version

19.0.3

PrimeNG version

19.0.0

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

20.11.0

Browser(s)

Edge

Steps to reproduce the behavior

1. Use the datepicker component with [showButtonBar]="true".
2. Open the datepicke

Expected behavior

The datepicker should display the button bar without error

Actual Behavior:
An error is thrown in the console and the button bar does not render properly.

[Delagen]

Seems this is issue: 61a7891#diff-40c9e8900181657297f7c0b31d5fee5a96cd1c1704f1d9f406b3bfcd8b1022a9R493

ngClass values wrapped in square brackets, that by default results in [undefined] and undefined is invalid value for class

[Delagen]

Workaround, set any classes for this buttons

    [todayButtonStyleClass]="'btn-bar-today'"
    [clearButtonStyleClass]="'btn-bar-clear'"