### The problem
When trying to install a blueprint, I unable to import it to my… instance and get a “unknown error”
### What version of Home Assistant Core has the issue?
2022.5.1
### What was the last working version of Home Assistant Core?
_No response_
### What type of installation are you running?
Home Assistant Core
### Integration causing the issue
Blueprint
### Link to integration documentation on our website
_No response_
### Diagnostics information
_No response_
### Example YAML snippet
_No response_
### Anything in the logs that might be useful for us?
```txt
Logger: homeassistant.components.websocket_api.http.connection
Source: util/yaml/dumper.py:40
Integration: Home Assistant WebSocket API (documentation, issues)
First occurred: 9:59:51 AM (3 occurrences)
Last logged: 10:55:38 AM
[281473022819968] Error handling message: Unknown error (unknown_error)
[281473195689248] Error handling message: Unknown error (unknown_error)
[281472622803600] Error handling message: Unknown error (unknown_error)
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/components/websocket_api/decorators.py", line 27, in _handle_async_response
await func(hass, connection, msg)
File "/usr/src/homeassistant/homeassistant/components/blueprint/websocket_api.py", line 125, in ws_save_blueprint
await domain_blueprints[domain].async_add_blueprint(blueprint, path)
File "/usr/src/homeassistant/homeassistant/components/blueprint/models.py", line 327, in async_add_blueprint
await self.hass.async_add_executor_job(
File "/usr/local/lib/python3.9/concurrent/futures/thread.py", line 58, in run
result = self.fn(*self.args, **self.kwargs)
File "/usr/src/homeassistant/homeassistant/components/blueprint/models.py", line 318, in _create_file
path.write_text(blueprint.yaml(), encoding="utf-8")
File "/usr/src/homeassistant/homeassistant/components/blueprint/models.py", line 107, in yaml
return yaml.dump(self.data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 13, in dump
return yaml.safe_dump(
File "/usr/local/lib/python3.9/site-packages/yaml/__init__.py", line 269, in safe_dump
return dump_all([data], stream, Dumper=SafeDumper, **kwds)
File "/usr/local/lib/python3.9/site-packages/yaml/__init__.py", line 241, in dump_all
dumper.represent(data)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 27, in represent
node = self.represent_data(data)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 56, in <lambda>
lambda dumper, value: represent_odict(dumper, "tag:yaml.org,2002:map", value),
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 40, in represent_odict
node_value = dumper.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 56, in <lambda>
lambda dumper, value: represent_odict(dumper, "tag:yaml.org,2002:map", value),
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 40, in represent_odict
node_value = dumper.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 56, in <lambda>
lambda dumper, value: represent_odict(dumper, "tag:yaml.org,2002:map", value),
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 40, in represent_odict
node_value = dumper.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 56, in <lambda>
lambda dumper, value: represent_odict(dumper, "tag:yaml.org,2002:map", value),
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 40, in represent_odict
node_value = dumper.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 207, in represent_dict
return self.represent_mapping('tag:yaml.org,2002:map', data)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 118, in represent_mapping
node_value = self.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 48, in represent_data
node = self.yaml_representers[data_types[0]](self, data)
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 56, in <lambda>
lambda dumper, value: represent_odict(dumper, "tag:yaml.org,2002:map", value),
File "/usr/src/homeassistant/homeassistant/util/yaml/dumper.py", line 40, in represent_odict
node_value = dumper.represent_data(item_value)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 58, in represent_data
node = self.yaml_representers[None](self, data)
File "/usr/local/lib/python3.9/site-packages/yaml/representer.py", line 231, in represent_undefined
raise RepresenterError("cannot represent an object", data)
yaml.representer.RepresenterError: ('cannot represent an object', <NumberSelectorMode.SLIDER: 'slider'>)
```
### Additional information
I first noticed the issue in the beta versions of 2022.5