Rare NPE in GlyphLayout

I have an Android app in the Play Store.
Rarely I see exceptions like this in the Google Play Console:

Exception java.lang.NullPointerException:
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:176)
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:95)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.computePrefSize (Label.java:162)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.scaleAndComputePrefSize (Label.java:147)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.getPrefWidth (Label.java:244)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.<init> (Label.java:75)

or:

(RuntimeException root cause)
Caused by java.lang.NullPointerException:
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.calculateWidths (GlyphLayout.java:280)
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:266)
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:95)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.computePrefSize (Label.java:162)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.scaleAndComputePrefSize (Label.java:147)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.getPrefWidth (Label.java:244)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.<init> (Label.java:75)

or, maybe related:

Exception java.lang.IndexOutOfBoundsException:
  at com.badlogic.gdx.utils.Array.get (Array.java:155)
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:215)
  at com.badlogic.gdx.graphics.g2d.GlyphLayout.setText (GlyphLayout.java:101)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.computePrefSize (Label.java:160)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.scaleAndComputePrefSize (Label.java:147)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.getPrefHeight (Label.java:253)
  at com.badlogic.gdx.scenes.scene2d.ui.Label.layout (Label.java:175)
  at com.badlogic.gdx.scenes.scene2d.ui.Widget.validate (Widget.java:88)
  at com.badlogic.gdx.scenes.scene2d.ui.Stack.layout (Stack.java:107)
  at com.badlogic.gdx.scenes.scene2d.ui.WidgetGroup.validate (WidgetGroup.java:104)
  at com.badlogic.gdx.scenes.scene2d.ui.VerticalGroup.layout (VerticalGroup.java:201)
  at com.badlogic.gdx.scenes.scene2d.ui.WidgetGroup.validate (WidgetGroup.java:104)
  at com.badlogic.gdx.scenes.scene2d.ui.ScrollPane.layout (ScrollPane.java:498)

It happens in different labels, but only in labels, and I'm not able to reproduce it.

libgdx version: 1.12.1

Any idea?

Start by inspecting GlyphLayout.setText and calculateWidths at the reported line numbers, then trace the Label constructor and its computePrefSize calls. The reports provide no reproduction or named test, so done would require identifying a reproducible cause and establishing a regression check or clearly scoped fix.