syntax_data: {"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"\"Unexpected"}]}
source_snippet:                             "Unexpected capture place, upvars={:#?}, upvar_index={:?}",
context_before:                             this.upvars.len() > upvar_index.index(),
context_after:                             this.upvars,