function invertMatrix4(srcMatrix, tgtMatrix = new Matrix4()) {
  if (typeof tgtMatrix.invert === 'function') {
    tgtMatrix.copy(srcMatrix).invert()
  } else {
    tgtMatrix.getInverse(srcMatrix)
  }
  return tgtMatrix
}
Helper for smoothing out the `m.getInverse(x)` --> `m.copy(x).invert()` conversion
that happened in ThreeJS r123.
@param {Matrix4} srcMatrix
@param {Matrix4} [tgtMatrix]