Start tracking internal errors in the FHIRPath visitor using absl::Status. This will allow for better error propagation as useful error code information (e.g. Unimplemented) can now be surfaced to users of the library.
Start tracking internal errors in the FHIRPath visitor using absl::Status. This will allow for better error propagation as useful error code information (e.g. Unimplemented) can now be surfaced to users of the library.

PiperOrigin-RevId: 307877506

google/fhir,google/fhir,google/fhir,google/fhir,google/fhir,google/fhir