"Math Processing Errors" on empty \overset and differences between preview and answer

Question

This answer revision has an expression which displayed correctly in a prior Mathjax version, and also displays correctly in the edit window, but displays as [Math Processing Error] in the answer.

Revision Source

**Hint** $\rm\ 2^{\large\color{#c00}2} 3^{\large\color{#0a0}3} \mid 2^{\large\color{#c00}{2I}} 3^{\large\color{#0a0}{2J}} 5^{\large2K}\!\cdots \overset{}\Rightarrow \color{#c00}{I\ge 1},\ \color{#0a0}{J\ge 2}\ \ $ by *existence* and *uniqueness* of prime factorizations.

Output

Hint $\rm\ 2^{\large\color{#c00}2} 3^{\large\color{#0a0}3} \mid 2^{\large\color{#c00}{2I}} 3^{\large\color{#0a0}{2J}} 5^{\large2K}\!\cdots \overset{}\Rightarrow \color{#c00}{I\ge 1},\ \color{#0a0}{J\ge 2}\ \ $ by existence and uniqueness of prime factorizations.

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Ditto for this answer revision.

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Update I should clarify some points. The bug(s) appear to be triggered by vestigial empty \overset expressions (probably left behind when I was pulled away from the computer in the middle of trying out different presentations). Since these expressions worked fine in the past, this may or may not indicate a bug in changes made in recent versions.

However, the fact that this error is raised only in the answer, and not in the preview, is surely another bug, since the preview rendering should correspond 100% to the answer.

Answer 1

The culprit in the first example seems to be the \overset{}\Rightarrow construct.

• With it (should produce a [Math Processing Error] until fixed)

  $\rm\ 2^{\large\color{#c00}2} 3^{\large\color{#0a0}3} \mid 2^{\large\color{#c00}{2I}} 3^{\large\color{#0a0}{2J}} 5^{\large2K}\!\cdots \overset{}\Rightarrow \color{#c00}{I\ge 1},\ \color{#0a0}{J\ge 2}\ \ $

• Replaced with \Rightarrow (should render as expected)

  $\rm\ 2^{\large\color{#c00}2} 3^{\large\color{#0a0}3} \mid 2^{\large\color{#c00}{2I}} 3^{\large\color{#0a0}{2J}} 5^{\large2K}\!\cdots \Rightarrow \color{#c00}{I\ge 1},\ \color{#0a0}{J\ge 2}\ \ $

I'm willing to bet that the \overset{}\equiv construct is the culprit in the second example.

Checking the error messages (MathJax context menu ⇒ Show Math As ⇒ Error Message) on the problematic formula gives

Error: Cannot read property 'style' of null

Debugging tips: use 'unpacked/MathJax.js', inspect 'MathJax.Hub.lastError' in the browser console

Doing something to the MathJax rendering (e.g., changing the Math Renderer) seems to make the error temporarily go away on the user's end, though re-loading the page seems to cause the error to return.