Handling broken pipelines in dagit

Right now when something is wrong w/ a pipeline definition, dagit will spew the error to the console and refuse to load.

Instead, it would be great to show the dagit UI and highlight which pipeline in the repository is broken

[tinkerware]

I ran across an issue that seems related. Going over the Inputs tutorial at https://dagster.readthedocs.io/en/stable/sections/learn/tutorial/inputs.html I ran the test pipeline first with an untyped solid, and then changed the same solid to use type signatures. The runs view refused to load with a GraphQL error: GraphQL error] Pipeline "hello_inputs_pipeline" config errors: Error 1: Type failure at path "root:solids:add_hello_to_word:inputs:word:value" on type "String". Value at path root:solids:add_hello_to_word:inputs:word:value is not valid. Expected "String".

The backtrace I see in the console is:

An error occurred while resolving field LogMessageConnection.nodes
Traceback (most recent call last):
  File "/Users/cagatay/.pyenv/versions/3.7.4/envs/dagster-3.7/lib/python3.7/site-packages/graphql/execution/executor.py", line 450, in resolve_or_error
    return executor.execute(resolve_fn, source, info, **args)
  File "/Users/cagatay/.pyenv/versions/3.7.4/envs/dagster-3.7/lib/python3.7/site-packages/graphql/execution/executors/sync.py", line 16, in execute
    return fn(*args, **kwargs)
  File "/Users/cagatay/.pyenv/versions/3.7.4/envs/dagster-3.7/lib/python3.7/site-packages/dagster_graphql/schema/runs.py", line 184, in resolve_nodes
    RunConfig(mode=self._pipeline_run.mode),
  File "/Users/cagatay/.pyenv/versions/3.7.4/envs/dagster-3.7/lib/python3.7/site-packages/dagster/core/execution/api.py", line 70, in create_execution_plan
    environment_config = create_environment_config(pipeline, environment_dict, run_config)
  File "/Users/cagatay/.pyenv/versions/3.7.4/envs/dagster-3.7/lib/python3.7/site-packages/dagster/core/execution/context_creation_pipeline.py", line 50, in create_environment_config
    raise DagsterInvalidConfigError(pipeline, result.errors, environment_dict)
dagster.core.errors.DagsterInvalidConfigError: Pipeline "hello_inputs_pipeline" config errors:
    Error 1: Type failure at path "root:solids:add_hello_to_word:inputs:word:value" on type "String". Value at path root:solids:add_hello_to_word:inputs:word:value is not valid. Expected "String".

This is somewhat annoying, since making type changes to your solids that are incompatible with previous runs in your history will blow up Dagit, until you manually excise the problematic runs from history (haven’t tried this yet, so not sure if it’s possible). Is this the same problem this issue is addressing and should create a new one?

[hellendag]

Closing in favor of #2718.