syntax_data: {"ast_node_type":"other","tokens":[{"end":88,"kind":"keyword","start":0,"text":"Err(NotConstEvaluatable::MentionsInfer)"}]}
source_snippet:                         Err(NotConstEvaluatable::MentionsInfer) => Ok(EvaluatedToAmbig),
context_before:                         Ok(()) => Ok(EvaluatedToOk),
context_after:                         Err(NotConstEvaluatable::MentionsParam) => Ok(EvaluatedToErr),