cwltool --validate is success --make-template becomes failure

## Expected Behavior

Output template something like this.

```
(cwlenv) ➜ create_issue cwltool --validate success.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'success.cwl' to 'file:///home/manabu/work/CWL/create_issue/success.cwl'
success.cwl is valid CWL.
(cwlenv) ➜ create_issue cwltool --make-template success.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'success.cwl' to 'file:///home/manabu/work/CWL/create_issue/success.cwl'
params: # array of "file:///home/manabu/work/CWL/create_issue/success.cwl#params/ParamPair" record type.
- param2: a_string # type 'string'
param1: a_string # type 'string'
```

## Actual Behavior

No template output.

```
(cwlenv) ➜ create_issue cwltool --validate problem.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'problem.cwl' to 'file:///home/manabu/work/CWL/create_issue/problem.cwl'
problem.cwl is valid CWL.
(cwlenv) ➜ create_issue cwltool --validate problem.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'problem.cwl' to 'file:///home/manabu/work/CWL/create_issue/problem.cwl'
problem.cwl is valid CWL.
(cwlenv) ➜ create_issue cwltool --make-template problem.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'problem.cwl' to 'file:///home/manabu/work/CWL/create_issue/problem.cwl'
ERROR I'm sorry, I couldn't load this CWL file, try again with --debug for more information.
The error was: 0

```

## Workflow Code

success.cwl

```
#!/usr/bin/env cwl-runner

cwlVersion: v1.2
class: CommandLineTool

inputs:
params:
type:
type: array
items:
- type: record
name: ParamPair
fields:
- name: param1
type: string
- name: param2
type: string
outputs: []

baseCommand: []
```

problem.cwl

```
#!/usr/bin/env cwl-runner

cwlVersion: v1.2
class: CommandLineTool

inputs:
params:
type:
type: array
items:
type: record
name: ParamPair
fields:
- name: param1
type: string
- name: param2
type: string
outputs: []

baseCommand: []
```

## Full Traceback

```pytb
(cwlenv) ➜ create_issue cwltool --debug --make-template problem.cwl
INFO /home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
INFO Resolved 'problem.cwl' to 'file:///home/manabu/work/CWL/create_issue/problem.cwl'
ERROR I'm sorry, I couldn't load this CWL file.
The error was:
Traceback (most recent call last):
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/cwltool/main.py", line 1135, in main
make_template(tool, stdout)
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/cwltool/main.py", line 754, in make_template
generate_input_template(tool),
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/cwltool/main.py", line 342, in generate_input_template
value, comment = generate_example_input(inp["type"], inp.get("default", None))
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/cwltool/main.py", line 204, in generate_example_input
example, comment = generate_example_input(inptype[0], default)
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/cwltool/main.py", line 222, in generate_example_input
first_item = cast(MutableSequence[CWLObjectType], inptype["items"])[0]
File "/home/manabu/work/CWL/create_issue/cwlenv/lib/python3.10/site-packages/ruamel/yaml/comments.py", line 851, in __getitem__
return ordereddict.__getitem__(self, key)
KeyError: 0
(cwlenv) ➜ create_issue

```

## Your Environment
* cwltool version:
Check using ``cwltool --version``

```
(cwlenv) ➜ create_issue cwltool --version
/home/manabu/work/CWL/create_issue/cwlenv/bin/cwltool 3.1.20231114134824
(cwlenv) ➜ create_issue
```