Looking in NB source files, it looks like they are expecting TextField.font to be an entry in UIDefaults.
There have been many issues of missing UiDefaults keys, although these keys are not required by any spec they are supported by Metal, Windows and many other common LAFs. I have added a comprehensive set to cover as many of these backwards compatibility issues. They are based on the reference page http://java.sun.com/products/jfc/tsc/articles/lookandfeel_reference/index.html
properties for all basic components and this set of standard colors:
desktop: Color of the desktop background
activeCaption: Color for captions (title bars) when they are active.
activeCaptionText: Text color for text in captions (title bars).
activeCaptionBorder: Border color for caption (title bar) window borders.
inactiveCaption: Color for captions (title bars) when not active.
inactiveCaptionText: Text color for text in inactive captions (title bars).
inactiveCaptionBorder: Border color for inactive caption (title bar) window borders.
window: Default color for the interior of windows
windowBorder: Color of the window's border
windowText: Color of the window's title text
menu: Background color for menus
menuText: Text color for menus
text: Text background color
textText: Text foreground color
textHighlight: Text background color when selected
textHighlightText: Text color when selected
textInactiveText: Text color when disabled
control: Default color for controls (buttons, sliders, etc)
controlText: Default color for text in controls
controlHighlight: Specular highlight (opposite of the shadow)
controlLtHighlight: Highlight color for controls
controlShadow: Shadow color for controls
controlDkShadow: Dark shadow color for controls
scrollbar: Scrollbar background (usually the "track")
info: information color (sometimes used for tooltips)
infoText: information text color (sometimes used for tooltips)