Report base error class

[hadley]

In #2283 we started entracing snapshots so that we get useful backtraces if snapshot code unexpectedly errors. This had the unfortunate side-effect of changing the reported class for expected errors. We now show the original message if it was an entraced error.

Fixes #2286.

[claude]

Claude finished @hadley's task —— View job

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The fix correctly addresses the issue where entraced errors were showing rlang_error class instead of the original error class. The error_class() function properly unwraps entraced errors to extract the original class.

Potential issue: The comment mentions this approach is "fragile" because entrace() doesn't document the x$error field behavior. Consider adding defensive checks:

error_class <- function(x) {
  # If error was entraced from base R error, use original error class  
  if (inherits(x, "rlang_error") && !is.null(x$error) && inherits(x$error, "condition")) {
    x <- x$error
  }
  class(x)[[1]]
}

This ensures x$error is actually a condition object before unwrapping.

[lionel-]

Looks good!