utilities to fix LaTeX issues

tests/test_gui_core.py

@@ -1785,6 +1785,18 @@ class StandardCliTests(unittest.TestCase):
             r"valid $\begin{cases} A=0 \\ B=1 \end{cases}$",
         )
         self.assertEqual(module.clean_string(cleaned_text, {}), cleaned_text)
+        percent_text = r"Code `n % p`, prose 50%, math $n \% p$ and $50%$."
+        escaped_percent_text = (
+            r"Code `n \% p`, prose 50\%, math $n \% p$ and $50\%$."
+        )
+        self.assertEqual(
+            module.clean_string(percent_text, {}),
+            escaped_percent_text,
+        )
+        self.assertEqual(
+            module.clean_string(escaped_percent_text, {}),
+            escaped_percent_text,
+        )
         corrupted_json_escapes = (
             "Formulas $"
             + "\x0c"