panicked

I get this when I compile one of my file:
```
thread '' panicked at 'called `Result::unwrap()` on an `Err` value: Error { kind: EMITTER, problem: "expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS" }', fontir/src/ir.rs:1099:41
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[2023-10-02T18:41:59.835228Z main fontc::workload ERROR] Fe(Glyph(cent)) failed Job panicked: 'called `Result::unwrap()` on an `Err` value: Error { kind: EMITTER, problem: "expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS" }'
At least one work item failed
```
This is one of my fonts. I can provide the file if needed but not over git.

Start at fontir/src/ir.rs:1099:41 and reproduce the panic with the affected font, using RUST_BACKTRACE=1 for context. Determine which input causes the YAML emitter error and confirm the compiler reports or handles it without panicking; the issue does not include the font file or a named test.

Written by the indexing model from the issue text.