# try_fetch() checks inputs

    Code
      (expect_error(try_fetch(NULL, function(...) NULL)))
    Output
      <error/rlang_error>
      Error in `try_fetch()`:
      ! `...` must be named with condition classes.

# can rethrow from `try_fetch()`

    Code
      err <- catch_error(try_fetch(f(), error = function(cnd) abort("bar", parent = cnd)))
      print(err)
    Output
      <error/rlang_error>
      Error:
      ! bar
      Caused by error in `h()`:
      ! foo
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(...)
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = cnd))
       10. | +-base::tryCatch(...)
       11. | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       12. | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       13. | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       14. | \-base::withCallingHandlers(...)
       15. \-rlang (local) f()
       16.   \-rlang (local) g()
       17.     \-rlang (local) h()
    Code
      print(err, simplify = "none")
    Output
      <error/rlang_error>
      Error:
      ! bar
      Caused by error in `h()`:
      ! foo
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(...)
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = cnd))
       10. | +-base::tryCatch(...)
       11. | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       12. | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       13. | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       14. | \-base::withCallingHandlers(...)
       15. \-rlang (local) f()
       16.   \-rlang (local) g()
       17.     \-rlang (local) h()
    Code
      err <- catch_error(high1(chain = TRUE))
      print(err)
    Output
      <error/rlang_error>
      Error in `high3()`:
      ! bar
      Caused by error in `h()`:
      ! foo
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(high1(chain = TRUE))
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. \-rlang (local) high1(chain = TRUE)
       10.   \-rlang (local) high2(...)
       11.     \-rlang (local) high3(...)
       12.       +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = cnd))
       13.       | +-base::tryCatch(...)
       14.       | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       15.       | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       16.       | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       17.       | \-base::withCallingHandlers(...)
       18.       \-rlang (local) f()
       19.         \-rlang (local) g()
       20.           \-rlang (local) h()
    Code
      print(err, simplify = "none")
    Output
      <error/rlang_error>
      Error in `high3()`:
      ! bar
      Caused by error in `h()`:
      ! foo
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(high1(chain = TRUE))
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. \-rlang (local) high1(chain = TRUE)
       10.   \-rlang (local) high2(...)
       11.     \-rlang (local) high3(...)
       12.       +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = cnd))
       13.       | +-base::tryCatch(...)
       14.       | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       15.       | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       16.       | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       17.       | \-base::withCallingHandlers(...)
       18.       \-rlang (local) f()
       19.         \-rlang (local) g()
       20.           \-rlang (local) h()
    Code
      err <- catch_error(high1(chain = FALSE))
      print(err)
    Output
      <error/rlang_error>
      Error in `high3()`:
      ! bar
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(high1(chain = FALSE))
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. \-rlang (local) high1(chain = FALSE)
       10.   \-rlang (local) high2(...)
       11.     \-rlang (local) high3(...)
       12.       +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = NA))
       13.       | +-base::tryCatch(...)
       14.       | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       15.       | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       16.       | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       17.       | \-base::withCallingHandlers(...)
       18.       \-rlang (local) f()
       19.         \-rlang (local) g()
       20.           \-rlang (local) h()
    Code
      print(err, simplify = "none")
    Output
      <error/rlang_error>
      Error in `high3()`:
      ! bar
      ---
      Backtrace:
           x
        1. +-rlang:::catch_error(high1(chain = FALSE))
        2. | \-rlang::catch_cnd(expr, "error")
        3. |   +-rlang::eval_bare(...)
        4. |   +-base::tryCatch(...)
        5. |   | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
        6. |   |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
        7. |   |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
        8. |   \-base::force(expr)
        9. \-rlang (local) high1(chain = FALSE)
       10.   \-rlang (local) high2(...)
       11.     \-rlang (local) high3(...)
       12.       +-rlang::try_fetch(f(), error = function(cnd) abort("bar", parent = NA))
       13.       | +-base::tryCatch(...)
       14.       | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
       15.       | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
       16.       | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
       17.       | \-base::withCallingHandlers(...)
       18.       \-rlang (local) f()
       19.         \-rlang (local) g()
       20.           \-rlang (local) h()