TypeError: unsupported operand type(s) for |: 'dict' and 'str'

[esnible]

Describe the bug
The following PDL program produces a backtrace and the output TypeError: unsupported operand type(s) for |: 'dict' and 'str'

To Reproduce
Use this program:

object:
  - defs:
      CONCLUSIONS:
        for:
          v: ["a", "b", "c"]
        repeat:
          data:
            ${ v }: ${ v }

Expected behavior
Either {"a": "a", "b": "b", "c": "c"} or a meaningful error message.

Desktop (please complete the following information):

• Version PDL 0.3.1.dev110+ga736767.d20250224

[esnible]

Note: I originally wanted to use join: instead of object:, like this:

for:
  i: [1, 2]
repeat:
  data:
     ${ i }: ${ i }
join:
  as: object # "object" is invalid here

However, the as only allows arrays or strings or "lastOf"; there is no no dict key-value merge type.