Fix index access panic

[julienduchesne]

Oops, the second "if" crashes

[github-actions]

Benchstat (compared to main):

name                                                                    old time/op  new time/op  delta
Definition/test_goto_definition_for_var_myvar-2                         5.73µs ± 1%  5.90µs ± 3%    ~     (p=0.095 n=5+5)
Definition/test_goto_definition_on_function_helper-2                    5.82µs ± 1%  5.84µs ± 0%    ~     (p=0.151 n=5+5)
Definition/test_goto_inner_definition-2                                 5.84µs ± 1%  5.82µs ± 1%    ~     (p=0.286 n=5+5)
Definition/test_goto_super_index-2                                      6.00µs ± 0%  6.01µs ± 2%    ~     (p=1.000 n=5+5)
Definition/test_goto_super_nested-2                                     5.99µs ± 1%  5.98µs ± 0%    ~     (p=1.000 n=5+5)
Definition/test_goto_self_object_field_function-2                       6.18µs ± 0%  6.18µs ± 0%    ~     (p=0.841 n=5+5)
Definition/test_goto_super_object_field_local_defined_obj_'foo'-2       6.44µs ± 1%  6.46µs ± 1%    ~     (p=1.000 n=5+5)
Definition/test_goto_super_object_field_local_defined_obj_'g'-2         6.54µs ± 0%  6.50µs ± 0%  -0.61%  (p=0.016 n=5+4)
Definition/test_goto_local_var_from_other_local_var-2                   5.15µs ± 1%  5.15µs ± 1%    ~     (p=0.730 n=5+5)
Definition/test_goto_local_obj_field_from_'self.attr'_from_other_obj-2  7.58µs ± 0%  7.65µs ± 1%  +0.85%  (p=0.024 n=5+5)
Definition/test_goto_local_object_'obj'_via_obj_index_'obj.foo'-2       6.02µs ± 0%  6.07µs ± 1%  +0.84%  (p=0.008 n=5+5)
Definition/test_goto_imported_file-2                                    16.3µs ± 1%  16.5µs ± 0%  +1.51%  (p=0.008 n=5+5)
Definition/test_goto_imported_file_at_lhs_index-2                       6.46µs ± 1%  6.49µs ± 0%  +0.60%  (p=0.032 n=5+5)
Definition/test_goto_imported_file_at_rhs_index-2                       6.49µs ± 1%  6.50µs ± 1%    ~     (p=0.587 n=5+5)
Definition/goto_import_index-2                                          5.88µs ± 0%  5.92µs ± 1%    ~     (p=0.056 n=5+5)
Definition/goto_attribute_of_nested_import-2                            7.40µs ± 0%  7.42µs ± 0%    ~     (p=0.111 n=5+5)
Definition/goto_dollar_attribute-2                                      6.53µs ± 1%  6.47µs ± 0%  -0.87%  (p=0.016 n=5+5)
Definition/goto_dollar_sub_attribute-2                                  7.07µs ± 0%  7.03µs ± 0%  -0.55%  (p=0.016 n=5+5)
Definition/goto_dollar_doesn't_follow_to_imports-2                      6.49µs ± 0%  6.43µs ± 1%  -0.99%  (p=0.008 n=5+5)
Definition/goto_attribute_of_nested_import_no_object_intermediary-2     6.60µs ± 1%  6.56µs ± 1%    ~     (p=0.095 n=5+5)
Definition/goto_self_in_import_in_binary-2                              40.2µs ± 1%  40.0µs ± 1%    ~     (p=0.421 n=5+5)
Definition/goto_self_attribute_from_local-2                             6.10µs ± 0%  6.07µs ± 0%  -0.62%  (p=0.008 n=5+5)
Definition/goto_function_parameter_from_inside_function-2               6.22µs ± 0%  6.22µs ± 2%    ~     (p=0.286 n=4+5)
Definition/goto_local_func_param-2                                      6.57µs ± 0%  6.52µs ± 0%  -0.69%  (p=0.016 n=5+5)
Definition/goto_self_complex_scope_1-2                                  6.78µs ± 0%  6.76µs ± 0%    ~     (p=0.222 n=5+5)
Definition/goto_self_complex_scope_2-2                                  7.46µs ± 1%  7.41µs ± 0%    ~     (p=0.095 n=5+5)
Definition/goto_with_overrides:_clobber_string-2                        93.1µs ± 1%  93.4µs ± 1%    ~     (p=0.905 n=5+4)
Definition/goto_with_overrides:_clobber_nested_string-2                 97.2µs ± 5%  95.8µs ± 1%    ~     (p=0.690 n=5+5)
Definition/goto_with_overrides:_clobber_map-2                           93.8µs ± 1%  93.7µs ± 1%    ~     (p=0.730 n=5+5)
Definition/goto_with_overrides:_map_(multiple_definitions)-2            95.0µs ± 1%  95.4µs ± 1%    ~     (p=0.548 n=5+5)
Definition/goto_with_overrides:_nested_map_(multiple_definitions)-2      104µs ± 2%   103µs ± 1%    ~     (p=0.095 n=5+5)
Definition/goto_with_overrides:_string_carried_from_super-2             93.5µs ± 1%  93.0µs ± 0%    ~     (p=0.151 n=5+5)
Definition/goto_with_overrides:_nested_string_carried_from_super-2      96.3µs ± 1%  96.1µs ± 1%    ~     (p=0.690 n=5+5)
Definition/goto_with_overrides:_string_carried_from_local-2             97.0µs ± 3%  96.8µs ± 2%    ~     (p=1.000 n=5+5)
Definition/goto_with_overrides:_string_carried_from_import-2             100µs ± 8%    96µs ± 1%  -4.52%  (p=0.008 n=5+5)
Definition/goto_with_overrides:_string_carried_from_second_import-2     96.9µs ± 1%  97.0µs ± 2%    ~     (p=0.841 n=5+5)
Definition/goto_deeply_nested_imported_attribute-2                      10.2µs ± 0%  10.2µs ± 1%  +0.73%  (p=0.040 n=5+5)
Definition/goto_deeply_nested_imported_attribute_through_self-2         46.5µs ± 1%  46.2µs ± 1%    ~     (p=0.690 n=5+5)
Definition/goto_computed_field_name_object_field-2                      6.37µs ± 0%  6.34µs ± 0%  -0.52%  (p=0.040 n=5+5)
Definition/goto_field_through_function-2                                6.79µs ± 1%  6.67µs ± 0%  -1.82%  (p=0.008 n=5+5)
Definition/goto_field_through_function-created_object-2                  135µs ± 1%   135µs ± 1%    ~     (p=0.841 n=5+5)
Definition/goto_field_through_builder_pattern_attribute-2               10.7µs ± 1%  10.7µs ± 1%    ~     (p=0.310 n=5+5)
Definition/goto_field_through_mixin_attribute-2                         8.74µs ± 1%  8.69µs ± 1%  -0.65%  (p=0.048 n=5+5)