Disabling `middle-word-em` breaks `(*em*)`

[justanotheranonymoususer]

Describe the bug
See example below

To Reproduce

import markdown2

markdown_text = """
**Strong** (*em*)
"""

html_output = markdown2.markdown(markdown_text, extras={
    'middle-word-em': {'allowed': False},
})

print(html_output)

Expected behavior

Expected:

<p><strong>Strong</strong> (<em>em</em>)</p>

Actual:

<p><strong>Strong</strong> (*em*)</p>

Debug info
Version of library being used: 8d50892

[justanotheranonymoususer]

Another test case, probably same root cause:

note:*this is good*, but *this is not*