Having an empty templateAttributes causes all attributes to be removed.

Given the following project.yml, MyTarget will be created with no template attributes. It seems like if anything contains an empty templateAttributes, it all cause all other attributes that may have some from another template to be ignored/removed.

targetTemplates:
  SomeTemplate:
    templateAttributes:
      someAttribute: "Some Value"
targets:
  MyTarget:
    templates:
    - SomeTemplate
    templateAttributes:

It's easy enough to work around by adding any attitude to the target.

    templateAttributes:
      _:

I'd assume xcodegen is trying to merge the dictionaries but the one from the target with no content is possibly being parsed into a string which cant be merged with the existing dictionary. So instead of throwing an error or using the current values in the dictionary, it's returning an empty one.

"By why have an empty templateAttributes in the first place?" you may be asking.
We have some tooling to automatically update the yml files for various reasons. Having the templateAttributes allows us to set where it should appear in the file. If we rely on the scripts to add it when needed, it'd probably be added to either the bottom of the file, or a random location since dictionaries are unordered.

Start by reproducing the issue with the project.yml example and trace how target and templateAttributes dictionaries are merged during project generation. The fix is done when an empty target-level templateAttributes preserves attributes inherited from SomeTemplate, with a regression test covering this case.