private/app/launcher: unwrap errors fully to avoid hiding cause#4783
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MatthewCroughan wants to merge 1 commit intoscionproto:masterfrom
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private/app/launcher: unwrap errors fully to avoid hiding cause#4783MatthewCroughan wants to merge 1 commit intoscionproto:masterfrom
MatthewCroughan wants to merge 1 commit intoscionproto:masterfrom
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It is worth noting that the inverse case (a config option being missing when it is required) is not fixed, and still behaves badly despite this pr. For example when
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As an example, before this commit, when a key was removed from the
struct that defines available configuration option for the toml file for
a given application such as the scion-dispatcher, it would fail without
reporting what key is present when it should be removed from the config
file, as follows:
error: loading config from file {file=/foo.toml}: strict mode: fields in the document are missing in the target struct
After this commit it will fail more informatively as follows:
error: loading config from file {file=/foo.toml}: strict mode: fields in the document are missing in the target struct &toml.StrictMissingError{Errors:[]t
oml.DecodeError{toml.DecodeError{message:"missing field", line:4, column:1, key:toml.Key{"general", "reconnect_to_dispatcher"}, human:"1| [general]\n2| config_dir = \"/etc/scion\"\n3| id = \"sd\"\n4| reconnect_to_dispatcher = true\n | ~~~~~~~~~~~~~~~~~~~~~
~~ missing field\n5|\n6| [log.console]\n7| level = \"info\""}}}
You can see the reason for the failure is the presence of the "reconnect_to_dispatcher" key, which no longer exists
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oncilla
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Jun 17, 2025
| func (a *Application) Run() { | ||
| if err := a.run(); err != nil { | ||
| fmt.Fprintf(a.getErrorWriter(), "fatal error: %v\n", err) | ||
| fmt.Fprintf(a.getErrorWriter(), "fatal error: %v\n %#v\n", err, errors.Unwrap(err)) |
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IMO, this still produces hard to read error messages.
Instead, I think you should use errors.As together with toml.StrictMissingError and toml.DecodeError
If error matches -> pretty print to stderr
I would also leave this line unchanged.
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Before this commit, when a key was removed from the struct that defines available configuration option for the toml file for a given application such as the scion-dispatcher, it would fail without reporting what key is present when it should be removed from the config file, as follows:
error: loading config from file {file=/foo.toml}: strict mode: fields in the document are missing in the target structAfter this commit it will fail more informatively as follows:
error: loading config from file {file=/foo.toml}: strict mode: fields in the document are missing in the target struct &toml.StrictMissingError{Errors:[]t oml.DecodeError{toml.DecodeError{message:"missing field", line:4, column:1, key:toml.Key{"general", "reconnect_to_dispatcher"}, human:"1| [general]\n2| config_dir = \"/etc/scion\"\n3| id = \"sd\"\n4| reconnect_to_dispatcher = true\n | ~~~~~~~~~~~~~~~~~~~~~ ~~ missing field\n5|\n6| [log.console]\n7| level = \"info\""}}}You can see the reason for the failure is the presence of the "reconnect_to_dispatcher" key, which no longer exists in 0.12, but did in 0.11.
I do not think this PR is necessarily the best way to accomplish or format this, but it was useful for me and is a good way to discuss the issue. If anyone else has a better idea, then please contribute it!