Uninformative error on self-conflicting types

I used the following OpenAPI schema:

{
  "components": {
    "schemas": {
      "Foo": {
        "allOf": [
          {
            "$ref": "#/components/schemas/Bar"
          },
          {
            "properties": {
              "value": {
                "type": "string"
              }
            }
          }
        ],
        "required": [
          "value"
        ]
      },
      "Bar": {
        "properties": {
          "value": {
            "type": "object"
          }
        }
      }
    }
  },
  "info": {
    "title": "",
    "version": "1.0"
  },
  "openapi": "3.0.1",
  "paths": {
  }
}

I expected an error saying that the type of value in Foo was ambiguous. I got:

thread 'main' panicked at /Users/[my_user]/.cargo/registry/src/index.crates.io-6f17d22bba15001f/typify-impl-0.0.15/src/merge.rs:265:70:
called `Result::unwrap()` on an `Err` value: ()

It seems silly in this example, but the original schema was 10000 lines long, so it was quite tedious to isolate the issue.

Meta

Progenitor version used was 0.5.0.
I used a build.rs file to invoke progenitor.

Start by reproducing the schema from the issue through a build.rs invocation, then inspect the merge logic reported in typify-impl/src/merge.rs around the failing unwrap. The fix is done when conflicting property types produce an informative error instead of a panic, with coverage for this self-conflicting allOf case.