Friendlier error message than `TypeError`

When neither --dsn is passed nor DATABASE_URL is set, SQL Runner prints a stack trace:

Running actions: query

jobrunner.run loop started
query: Copying in code from /Users/iaindillingham/Code/opensafely/tpp-database-schema
query: Preparing
query: Executing
query: Logs written to: /Users/iaindillingham/Code/opensafely/tpp-database-schema/metadata/query.log
query: Finalizing
query: Job exited with error code 1
query: Cleaning up container and volume

=> query
   Job exited with error code 1

   log file: metadata/query.log
   outputs:
     (no outputs)

   logs:

     Traceback (most recent call last):
       File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
         return _run_code(code, main_globals, None,
       File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
         exec(code, run_globals)
       File "/app/sqlrunner/__main__.py", line 9, in <module>
         results = main.run_sql(dsn=args.dsn, sql_query=sql_query)
       File "/app/sqlrunner/main.py", line 51, in run_sql
         database=parsed_dsn.path.strip("/"),
     TypeError: a bytes-like object is required, not 'str'

parsed_dsn is an instance of ParseResultBytes rather than ParseResult because dsn was None:

https://github.com/opensafely-core/sqlrunner/blob/b6b77a26e10db589e467a180b3121c8c15a39ca0/sqlrunner/main.py#L44

The traceback points to sqlrunner/main.py around line 44, with entry-point behavior shown in sqlrunner/main.py. Start by reproducing the run without --dsn or DATABASE_URL and inspect how that input is parsed. Done means the failure produces a friendlier error instead of the shown TypeError and stack trace.