TypeError: 'String' object does not support item assignment when pyproject.toml is malformed

[lmmx]

Steps to reproduce

git clone https://git.launchpad.net/beautifulsoup
cd beautifulsoup
pdm init -v

Actual behavior

louis 🚶 ~/dev/beautifulsoup $ pdm init -v
pyproject.toml already exists, update it now.                                                                                                                                                    
Please enter the Python interpreter to use                                                                                                                                                       
0. /home/louis/miniconda3/bin/python (3.10)                                                                                                                                                      
1. /home/louis/miniconda3/bin/python3.10 (3.10)                                                                                                                                                  
2. /usr/bin/python3.10 (3.10)                                                                                                                                                                    
Please select (0):                                                                                                                                                                               
Is the project a library that is installable?                                                                                                                                                    
If yes, we will need to ask a few more questions to include the project name and build                                                                                                           
backend [y/n] (n): y                                                                                                                                                                             
Project name (beautifulsoup):                                                                                                                                                                    
Project version (0.1.0):                                                                                                                                                                         
Project description ():                                                                                                                                                                          
Which build backend to use?                                                                                                                                                                      
0. pdm-backend                                                                                                                                                                                   
1. setuptools                                                                                                                                                                                    
2. flit-core                                                                                                                                                                                     
3. hatchling                                                                                                                                                                                     
4. pdm-pep517                                                                                                                                                                                    
Please select (0):                                                                                                                                                                               
License(SPDX name) (MIT):                                                                                                                                                                        
Author name (Louis Maddox):                                                                                                                                                                      
Author email (louismmx@gmail.com):                                                                                                                                                               
Python requires('*' to allow any) (>=3.10):                                                                                                                                                      
Traceback (most recent call last):                                                                                                                                                               
  File "/home/louis/miniconda3/bin/pdm", line 8, in <module>                                                                                                                                     
    sys.exit(main())                                                                                                                                                                             
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/core.py", line 290, in main                                                                                                      
    return Core().main(args or sys.argv[1:])                                                                                                                                                     
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/core.py", line 208, in main                                                                                                      
    raise cast(Exception, err).with_traceback(traceback) from None                                                                                                                               
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/core.py", line 203, in main                                                                                                      
    self.handle(project, options)                                                                                                                                                                
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/core.py", line 157, in handle                                                                                                    
    command.handle(project, options)                                                                                                                                                             
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/commands/init.py", line 243, in handle                                                                                       
    self.do_init(project, options=options)                                                                                                                                                       
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/commands/init.py", line 38, in do_init                                                                                       
    self._init_builtin(project, options)                                                                                                                                                         
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/commands/init.py", line 79, in _init_builtin                                                                                 
    template.generate(project.root, metadata)                                                                                                                                                    
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/templates/__init__.py", line 78, in generate                                                                                 
    self._generate_pyproject(target_path / "pyproject.toml", metadata)                                                                                                                           
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/templates/__init__.py", line 130, in _generate_pyproject                                                                     
    merge_dictionary(content, template_content)                                                                                                                                                  
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/utils.py", line 644, in merge_dictionary                                                                                     
    merge_dictionary(target[key], value, append_array=append_array)                                                                                                                              
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/utils.py", line 644, in merge_dictionary                                                                                     
    merge_dictionary(target[key], value, append_array=append_array)                                                                                                                              
  File "/home/louis/miniconda3/lib/python3.10/site-packages/pdm/cli/utils.py", line 642, in merge_dictionary                                                                                     
    target[key] = value                                                                                                                                                                          
TypeError: 'String' object does not support item assignment 

Expected behavior

Environment Information

PDM version:
  2.8.2
Python Interpreter:
  /home/louis/miniconda3/bin/python (3.10)
Project Root:
  /home/louis/dev/beautifulsoup
Local Packages:
  
{
  "implementation_name": "cpython",
  "implementation_version": "3.10.6",
  "os_name": "posix",
  "platform_machine": "x86_64",
  "platform_release": "5.15.0-43-generic",
  "platform_system": "Linux",
  "platform_version": "#46-Ubuntu SMP Tue Jul 12 10:30:17 UTC 2022",
  "python_full_version": "3.10.6",
  "platform_python_implementation": "CPython",
  "python_version": "3.10",
  "sys_platform": "linux"
}

I inspected with a breakpoint at the error site at the end of the traceback and can see target is being assigned as "MIT" hence the error.

The type annotation is for a Mapping[str,str] so something has gone wrong.

This library is using a bad license value in its pyproject.toml (just a str not a dict type). I thought you might want to know that it crashes pdm init though and maybe pdm would be better exitting with a message about what failed to validate.

[frostming]

Exact same steps and I cannot reproduce, what is it version of tomlkit are you using? Run pdm self list|grep tomlkit to see it.

[lmmx]

Huh, weird! Latest version

tomlkit                       0.12.1      Style preserving TOML library