Trac #34760: latex of empty SkewPartition is broken

{{{
sage: p = SkewPartition([[],[]])
sage: latex(p)
------------------------------------------------------------------------
---
ValueError                                Traceback (most recent call
last)
Input In [9], in <cell line: 1>()
----> 1 latex(p)

File ~/sage-develop/src/sage/misc/latex.py:929, in
LatexCall.__call__(self, x, combine_all)
    898 r"""
    899 Return a :class:`LatexExpr` built out of the argument ``x``.
    900
   (...)
    926     x 2
    927 """
    928 if has_latex_attr(x):
--> 929     return LatexExpr(x._latex_())
    930 try:
    931     f = latex_table[type(x)]

File ~/sage-develop/src/sage/combinat/skew_partition.py:254, in
SkewPartition._latex_(self)
    235 def _latex_(self):
    236     r"""
    237     Return a `\LaTeX` representation of ``self``.
    238
   (...)
    252         }
    253     """
--> 254     return self.parent().options._dispatch(self, '_latex_',
'latex')

File ~/sage-develop/src/sage/structure/global_options.py:1690, in
GlobalOptions._dispatch(self, obj, dispatch_to, option, *args, **kargs)
   1688         dispatch_to = dispatch_to[:-1]
   1689     dispatch = getattr(obj, dispatch_to + '_' +
self._value[option])
-> 1690     return dispatch(*args, **kargs)
   1692 raise ValueError('%s is not a dispatchable option!' % option)

File ~/sage-develop/src/sage/combinat/skew_partition.py:306, in
SkewPartition._latex_young_diagram(self)
    304     for j in range(skew_size):
    305         arr[i][j] = None
--> 306 return tex_from_array(arr)

File ~/sage-develop/src/sage/combinat/output.py:175, in
tex_from_array(array, with_lines)
    173 lr=lr_macro.substitute(bar='|' if with_lines else '')
    174 if Tableaux.options.convention == "English":
--> 175     return '{%s\n%s\n}' % (lr, tex_from_skew_array(array,
with_lines))
    176 else:
    177     return '{%s\n%s\n}' % (lr, tex_from_skew_array(array[::-1],
with_lines, align='t'))

File ~/sage-develop/src/sage/combinat/output.py:309, in
tex_from_skew_array(array, with_lines, align)
    306     end_line=lambda r: r'\\'
    308 # now we draw the array
--> 309 tex=r'\raisebox{-.6ex}{$\begin{array}[%s]{*{%s}c}'%(align,max(ma
p(len,array)))
    310 tex+=end_line(0)+'\n'
    311 for r in range(len(array)):

ValueError: max() arg is an empty sequence
}}}

URL: https://trac.sagemath.org/34760
Reported by: mantepse
Ticket author(s): Martin Rubey
Reviewer(s): Christian Stump

Author: Release Manager

src/sage/combinat/skew_partition.py

@@ -268,8 +268,16 @@ def _latex_diagram(self):
             &\lr{\ast}&\lr{\ast}\\\cline{2-3}
             \end{array}$}
             }
+
+        TESTS:
+
+        Check that :trac:`34760` is fixed::
+
+            sage: print(SkewPartition([[],[]])._latex_diagram())
+            {\emptyset}
+
         """
-        if len(self._list) == 0:
+        if not any(self._list):
             return "{\\emptyset}"
 
         char = self.parent().options.latex_diagram_str
@@ -295,8 +303,15 @@ def _latex_young_diagram(self):
             &\lr{\phantom{x}}&\lr{\phantom{x}}\\\cline{2-3}
             \end{array}$}
             }
+
+        TESTS:
+
+        Check that :trac:`34760` is fixed::
+
+            sage: print(SkewPartition([[],[]])._latex_young_diagram())
+            {\emptyset}
         """
-        if len(self._list) == 0:
+        if not any(self._list):
             return "{\\emptyset}"
 
         from sage.combinat.output import tex_from_array
@@ -320,8 +335,15 @@ def _latex_marked(self):
             \lr{X}&\lr{\phantom{x}}&\lr{\phantom{x}}\\\cline{1-3}
             \end{array}$}
             }
+
+        TESTS:
+
+        Check that :trac:`34760` is fixed::
+
+            sage: print(SkewPartition([[],[]])._latex_marked())
+            {\emptyset}
         """
-        if len(self._list) == 0:
+        if not any(self._list):
             return "{\\emptyset}"
 
         from sage.combinat.output import tex_from_array