codegen all languages: issue nicer error message in the event of invalid YAML

[mr-c]

Example from cwl-utils:

env3.11) michael@mrc-tux:~/cwl-utils$ python3 dump_test.py 
Traceback (most recent call last):
  File "/home/michael/cwl-utils/dump_test.py", line 12, in <module>
    cwl_obj = load_document_by_uri(cwl_file)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/cwl_utils/parser/__init__.py", line 183, in load_document_by_uri
    return load_document_by_string(doc, real_uri, loadingOptions, id_, load_all)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/cwl_utils/parser/__init__.py", line 210, in load_document_by_string
    result = yaml.load(string)
             ^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/main.py", line 426, in load
    return constructor.get_single_data()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/constructor.py", line 111, in get_single_data
    node = self.composer.get_single_node()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/composer.py", line 64, in get_single_node
    self.parser.get_event()
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/parser.py", line 158, in get_event
    self.current_event = self.state()
                         ^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/parser.py", line 173, in parse_stream_start
    token = self.scanner.get_token()
            ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 1763, in get_token
    self._gather_comments()
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 1757, in _gather_comments
    self.fetch_more_tokens()
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 292, in fetch_more_tokens
    return self.fetch_literal()
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 675, in fetch_literal
    self.fetch_block_scalar(style='|')
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 686, in fetch_block_scalar
    self.tokens.append(self.scan_block_scalar(style))
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 1919, in scan_block_scalar
    return Scanner.scan_block_scalar(self, style, rt=rt)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 1104, in scan_block_scalar
    chomping, increment = self.scan_block_scalar_indicators(start_mark)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/michael/cwl-utils/env3.11/lib/python3.11/site-packages/ruamel/yaml/scanner.py", line 1256, in scan_block_scalar_indicators
    raise ScannerError(
ruamel.yaml.scanner.ScannerError: while scanning a block scalar
  in "<unicode string>", line 1, column 1:
    |Linux Build Status| |Code cover ... 
    ^ (line: 1)
expected chomping or indentation indicators, but found 'L'
  in "<unicode string>", line 1, column 2:
    |Linux Build Status| |Code covera ... 
     ^ (line: 1)

[tom-tan]

Is this an issue to improve the error messages by the code generator in schema_salad or an issue to improve the messages by code generated parsers?

[mr-c]

an issue to improve the messages by code generated parsers?

This one

[mr-c]

So the Python generated code should catch ruamel.yaml.scanner.ScannerError when calling ruamel.yaml functions and report it without the stacktrace; probably similar needed for the other languages