patch: fix NoneType error for 'visit_Case' function in c_generator.py when a case is empty by adding none type checker

Author: kmg3821

pycparser/c_generator.py

@@ -305,8 +305,9 @@ def visit_Switch(self, n):
 
     def visit_Case(self, n):
         s = 'case ' + self.visit(n.expr) + ':\n'
-        for stmt in n.stmts:
-            s += self._generate_stmt(stmt, add_indent=True)
+        if n.stmts is not None : 
+            for stmt in n.stmts:
+                s += self._generate_stmt(stmt, add_indent=True)
         return s
 
     def visit_Default(self, n):