fix: avoid ValueError on malformed CASE with reindent_aligned

sqlparse/filters/aligned_indent.py

@@ -68,23 +68,36 @@ def _process_identifierlist(self, tlist):
     def _process_case(self, tlist):
         offset_ = len('case ') + len('when ')
         cases = tlist.get_cases(skip_ws=True)
-        # align the end as well
+        # align the end as well (skip when END is missing or nested)
         end_token = tlist.token_next_by(m=(T.Keyword, 'END'))[1]
         # END is missing on malformed input, e.g. when an inner BEGIN ... END
         # block closed the CASE.
         if end_token is not None:
             cases.append((None, [end_token]))
+        if not cases:
+            return
 
         condition_width = [len(' '.join(map(str, cond))) if cond else 0
                            for cond, _ in cases]
         max_cond_width = max(condition_width, default=0)
 
         for i, (cond, value) in enumerate(cases):
             # cond is None when 'else or end'
-            stmt = cond[0] if cond else value[0]
+            if cond:
+                stmt = cond[0]
+            elif value:
+                stmt = value[0]
+            else:
+                continue
+            if stmt is None:
+                continue
 
             if i > 0:
-                tlist.insert_before(stmt, self.nl(offset_ - len(str(stmt))))
+                try:
+                    tlist.insert_before(stmt, self.nl(offset_ - len(str(stmt))))
+                except ValueError:
+                    # Token is not a direct child (malformed CASE) — leave as-is.
+                    continue
             if cond:
                 ws = sql.Token(T.Whitespace, self.char * (
                     max_cond_width - condition_width[i]))

tests/test_format.py

@@ -346,6 +346,12 @@ def test_window_functions(self):
             '  from table'])
 
 
+
+    def test_malformed_case_does_not_raise(self):
+        # issue #886
+        sql = "CASE 'a' := WHERE END SELECT GO # ->>"
+        assert isinstance(self.formatter(sql), str)
+
 class TestSpacesAroundOperators:
     @staticmethod
     def formatter(sql):

tests/test_regressions.py

@@ -527,3 +527,12 @@ def test_max_recursion(limit_recursion):
 ])
 def test_format_malformed_input_does_not_crash(sql, options):
     assert isinstance(sqlparse.format(sql, **options), str)
+
+
+def test_reindent_aligned_malformed_case_no_valueerror_issue886():
+    # Malformed CASE where END is nested inside an assignment group used to
+    # raise ValueError from token_index(None) inside AlignedIndentFilter.
+    sql = "CASE 'a' := WHERE END SELECT GO # ->>"
+    out = sqlparse.format(sql, reindent_aligned=True)
+    assert isinstance(out, str)
+    assert 'CASE' in out