message: Fix isInterpolatedProperty.
  Avoid possible exceptions when the value to be tested by
  isInterpolatedProperty is null.
diff: @@ -65,7 +65,7 @@ export function isInterpolatedPropertyDefinition<T>(
  */
  export function isInterpolatedProperty(p: any): p is InterpolatedProperty {
  if (
  - p !== undefined &&
  + p &&
  p.interpolationMode !== undefined &&
  p.zoomLevels instanceof Float32Array &&
  p.values !== undefined &&
  