Default to text style if style not specified.

tfpf · tfpf · commit b7dee27a5e5e · 2022-05-11T19:16:27.000+05:30
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -1792,7 +1792,7 @@ def set_names_and_parse_actions():
             "{" + Optional(p.ambi_delim | p.left_delim)("ldelim") + "}"
             + "{" + Optional(p.ambi_delim | p.right_delim)("rdelim") + "}"
             + "{" + p.float_literal("rulesize") + "}"
-            + "{" + p.style_literal("style") + "}"
+            + "{" + Optional(p.style_literal)("style") + "}"
             + p.required_group("num")
             + p.required_group("den")
             | Error("Expected "
@@ -2338,7 +2338,8 @@ def _genfrac(self, ldelim, rdelim, rule, style, num, den):
     def genfrac(self, s, loc, toks):
         return self._genfrac(
             toks.get("ldelim", ""), toks.get("rdelim", ""),
-            toks["rulesize"], self._MathStyle(toks["style"]),
+            toks["rulesize"], self._MathStyle(
+                toks.get("style", self._MathStyle.TEXTSTYLE.value)),
             toks["num"], toks["den"])
 
     def frac(self, s, loc, toks):
