feat: add error code unauthorized (#313)

* feat: add error code unauthorized

This makes it possible to check for an invalid token using
`hcloud.IsError(err, hcloud.ErrorCodeUnauthorized)`.

* docs: cleanup error codes comments

The "header" comment previously showed up for the first error code of
that category. By adding an empty line inbetween the two are no longer
connected.

By using "Deprecated: " tooling will automatically show a deprecation
warning for the `ErrorCodeLimitReached` constant.

hcloud/error.go

@@ -16,6 +16,7 @@ const (
 	ErrorCodeNotFound              ErrorCode = "not_found"               // Resource not found
 	ErrorCodeInvalidInput          ErrorCode = "invalid_input"           // Validation error
 	ErrorCodeForbidden             ErrorCode = "forbidden"               // Insufficient permissions
+	ErrorCodeUnauthorized          ErrorCode = "unauthorized"            // Request was made with an invalid or unknown token
 	ErrorCodeJSONError             ErrorCode = "json_error"              // Invalid JSON in request
 	ErrorCodeLocked                ErrorCode = "locked"                  // Item is locked (Another action is running)
 	ErrorCodeResourceLimitExceeded ErrorCode = "resource_limit_exceeded" // Resource limit exceeded
@@ -29,13 +30,15 @@ const (
 	ErrorUnsupportedError          ErrorCode = "unsupported_error"       // The given resource does not support this
 
 	// Server related error codes.
+
 	ErrorCodeInvalidServerType     ErrorCode = "invalid_server_type"     // The server type does not fit for the given server or is deprecated
 	ErrorCodeServerNotStopped      ErrorCode = "server_not_stopped"      // The action requires a stopped server
 	ErrorCodeNetworksOverlap       ErrorCode = "networks_overlap"        // The network IP range overlaps with one of the server networks
 	ErrorCodePlacementError        ErrorCode = "placement_error"         // An error during the placement occurred
 	ErrorCodeServerAlreadyAttached ErrorCode = "server_already_attached" // The server is already attached to the resource
 
 	// Load Balancer related error codes.
+
 	ErrorCodeIPNotOwned                       ErrorCode = "ip_not_owned"                          // The IP you are trying to add as a target is not owned by the Project owner
 	ErrorCodeSourcePortAlreadyUsed            ErrorCode = "source_port_already_used"              // The source port you are trying to add is already in use
 	ErrorCodeCloudResourceIPNotAllowed        ErrorCode = "cloud_resource_ip_not_allowed"         // The IP you are trying to add as a target belongs to a Hetzner Cloud resource
@@ -47,15 +50,18 @@ const (
 	ErrorCodeLoadBalancerNotAttachedToNetwork ErrorCode = "load_balancer_not_attached_to_network" // The Load Balancer is not attached to a network
 
 	// Network related error codes.
+
 	ErrorCodeIPNotAvailable     ErrorCode = "ip_not_available"        // The provided Network IP is not available
 	ErrorCodeNoSubnetAvailable  ErrorCode = "no_subnet_available"     // No Subnet or IP is available for the Load Balancer/Server within the network
 	ErrorCodeVSwitchAlreadyUsed ErrorCode = "vswitch_id_already_used" // The given Robot vSwitch ID is already registered in another network
 
 	// Volume related error codes.
+
 	ErrorCodeNoSpaceLeftInLocation ErrorCode = "no_space_left_in_location" // There is no volume space left in the given location
 	ErrorCodeVolumeAlreadyAttached ErrorCode = "volume_already_attached"   // Volume is already attached to a server, detach first
 
 	// Firewall related error codes.
+
 	ErrorCodeFirewallAlreadyApplied   ErrorCode = "firewall_already_applied"    // Firewall was already applied on resource
 	ErrorCodeFirewallAlreadyRemoved   ErrorCode = "firewall_already_removed"    // Firewall was already removed from the resource
 	ErrorCodeIncompatibleNetworkType  ErrorCode = "incompatible_network_type"   // The Network type is incompatible for the given resource
@@ -64,6 +70,7 @@ const (
 	ErrorCodeFirewallResourceNotFound ErrorCode = "firewall_resource_not_found" // Resource a firewall should be attached to / detached from not found
 
 	// Certificate related error codes.
+
 	ErrorCodeCAARecordDoesNotAllowCA                        ErrorCode = "caa_record_does_not_allow_ca"                          // CAA record does not allow certificate authority
 	ErrorCodeCADNSValidationFailed                          ErrorCode = "ca_dns_validation_failed"                              // Certificate Authority: DNS validation failed
 	ErrorCodeCATooManyAuthorizationsFailedRecently          ErrorCode = "ca_too_many_authorizations_failed_recently"            // Certificate Authority: Too many authorizations failed recently
@@ -72,12 +79,13 @@ const (
 	ErrorCodeCloudNotVerifyDomainDelegatedToZone            ErrorCode = "could_not_verify_domain_delegated_to_zone"             // Could not verify domain delegated to zone
 	ErrorCodeDNSZoneNotFound                                ErrorCode = "dns_zone_not_found"                                    // DNS zone not found
 
-	// Deprecated error codes
-	// The actual value of this error code is limit_reached. The new error code
-	// rate_limit_exceeded for ratelimiting was introduced before Hetzner Cloud
-	// launched into the public. To make clients using the old error code still
-	// work as expected, we set the value of the old error code to that of the
-	// new error code.
+	// Deprecated error codes.
+
+	// Deprecated: The actual value of this error code is limit_reached. The
+	// new error code rate_limit_exceeded for rate limiting was introduced
+	// before Hetzner Cloud launched into the public. To make clients using the
+	// old error code still work as expected, we set the value of the old error
+	// code to that of the new error code.
 	ErrorCodeLimitReached = ErrorCodeRateLimitExceeded
 )