SOURCE_FILE
  ERROR
    LET_KW "let"
    WHITESPACE " "
    IDENT_PAT
      NAME
        IDENT "foo"
    WHITESPACE " "
    EQ "="
    WHITESPACE " "
    RANGE_EXPR
      LITERAL
        INT_NUMBER "1"
      DOT2 ".."
      BLOCK_EXPR
        STMT_LIST
          L_CURLY "{"
          WHITESPACE "\n    "
          LITERAL
            INT_NUMBER "1"
          WHITESPACE "\n"
          R_CURLY "}"
    WHITESPACE " "
    LET_ELSE
      ELSE_KW "else"
      WHITESPACE " "
      BLOCK_EXPR
        STMT_LIST
          L_CURLY "{"
          WHITESPACE "\n    "
          EXPR_STMT
            RETURN_EXPR
              RETURN_KW "return"
            SEMICOLON ";"
          WHITESPACE "\n"
          R_CURLY "}"
    SEMICOLON ";"
  WHITESPACE "\n"
error 0: expected an item
error 22: right curly brace `}` before `else` in a `let...else` statement not allowed
