I cannot update a custom module when I add a report to it. 

report.xml

        
            Offer Report
            offer.offer
            qweb-pdf
            offer_letter_template.offer_report
            offer_letter_template.offer_report
            
            report
        


        
            
                
                    
                        

                            
Report title

                            
This object's name is
                                
                            

                        

                    
                
            
        
manifest data:

# always loaded
'data': [
    'security/ir.model.access.csv',
    'views/menus.xml',
    # 'views/templates.xml',
    'report/reports.xml',
],

when I update the module I get 

Odoo Server Error

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_http.py", line 237, in _dispatch
    result = request.dispatch()
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 684, in dispatch
    result = self._call_function(**self.params)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 360, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/service/model.py", line 94, in wrapper
    return f(dbname, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 348, in checked_call
    result = self.endpoint(*a, **kw)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 913, in __call__
    return self.method(*args, **kw)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 532, in response_wrap
    response = f(*args, **kw)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1393, in call_button
    action = self._call_kw(model, method, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/web/controllers/main.py", line 1381, in _call_kw
    return call_kw(request.env[model], method, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/api.py", line 399, in call_kw
    result = _call_kw_multi(method, model, args, kwargs)
  File "/usr/lib/python3/dist-packages/odoo/api.py", line 386, in _call_kw_multi
    result = method(recs, *args, **kwargs)
  File "", line 2, in button_immediate_upgrade
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_module.py", line 74, in check_and_log
    return method(self, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_module.py", line 654, in button_immediate_upgrade
    return self._button_immediate_function(type(self).button_upgrade)
  File "/usr/lib/python3/dist-packages/odoo/addons/base/models/ir_module.py", line 593, in _button_immediate_function
    modules.registry.Registry.new(self._cr.dbname, update_module=True)
  File "/usr/lib/python3/dist-packages/odoo/modules/registry.py", line 89, in new
    odoo.modules.load_modules(registry._db, force_demo, status, update_module)
  File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 457, in load_modules
    force, status, report, loaded_modules, update_module, models_to_check)
  File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 349, in load_marked_modules
    perform_checks=perform_checks, models_to_check=models_to_check
  File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 222, in load_module_graph
    load_data(cr, idref, mode, kind='data', package=package)
  File "/usr/lib/python3/dist-packages/odoo/modules/loading.py", line 69, in load_data
    tools.convert_file(cr, package.name, filename, idref, mode, noupdate, kind)
  File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 733, in convert_file
    convert_xml_import(cr, module, fp, idref, mode, noupdate)
  File "/usr/lib/python3/dist-packages/odoo/tools/convert.py", line 782, in convert_xml_import
    relaxng.assert_(doc)
  File "src/lxml/etree.pyx", line 3547, in lxml.etree._Validator.assert_
Exception

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 640, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/usr/lib/python3/dist-packages/odoo/http.py", line 316, in _handle_exception
    raise exception.with_traceback(None) from new_cause
AssertionError: Document does not comply with schema