ToggleSpeakMode causes error

[NSoiffer]

Starting with the following MathML (probably doesn't matter)

  <math>
    <mfrac>
      <mrow><mi>x</mi><mo>+</mo><mn>1</mn></mrow>
      <mrow><mi>y</mi><mo>-</mo><mn>2</mn></mrow>
    </mfrac>
  </math>

Press Shift+Space (ToggleSpeakMode). Result "overview of expression after move; fraction".

Press Shift+Space again, same thing spoken (didn't toggle).

Zoom in: " in numerator; x plus 1"

Press Shift+Space again. You get the following error:

Internal error: With en/SimpleSpeak in Enhanced mode, can't ToggleSpeakMode from expression with id 'Mnwvjays-2' inside:
   <math data-from-mathml='math' id='Mnwvjays-0' data-id-added='true'>
	<fraction data-from-mathml='mfrac' id='Mnwvjays-1' data-id-added='true' data-nemeth-frac-level='⠠'>
	  <mrow data-from-mathml='mrow' id='Mnwvjays-2' data-id-added='true'>
		<mi data-from-mathml='mi' id='Mnwvjays-3' data-id-added='true'>𝑥</mi>
		<mo data-from-mathml='mo' id='Mnwvjays-4' data-id-added='true'>+</mo>
		<mn data-from-mathml='mn' id='Mnwvjays-5' data-id-added='true'>1</mn>
	  </mrow>
	  <mrow data-from-mathml='mrow' id='Mnwvjays-6' data-id-added='true'>
		<mi data-from-mathml='mi' id='Mnwvjays-7' data-id-added='true'>𝑦</mi>
		<mo data-from-mathml='mo' id='Mnwvjays-8' data-id-added='true'>-</mo>
		<mn data-from-mathml='mn' id='Mnwvjays-9' data-id-added='true'>2</mn>
	  </mrow>
	</fraction>
   </math>