Possible values:

• 'cancelled': The operation was cancelled (typically by the caller).
• 'unknown': Unknown error or an error from a different error domain.
• 'invalid-argument': Client specified an invalid argument. Note that thisdiffers from 'failed-precondition'. 'invalid-argument' indicatesarguments that are problematic regardless of the state of the system(e.g. an invalid field name).
• 'deadline-exceeded': Deadline expired before operation could complete.For operations that change the state of the system, this error may bereturned even if the operation has completed successfully. For example,a successful response from a server could have been delayed long enoughfor the deadline to expire.
• 'not-found': Some requested document was not found.
• 'already-exists': Some document that we attempted to create alreadyexists.
• 'permission-denied': The caller does not have permission to execute thespecified operation.
• 'resource-exhausted': Some resource has been exhausted, perhaps aper-user quota, or perhaps the entire file system is out of space.
• 'failed-precondition': Operation was rejected because the system is notin a state required for the operation's execution.
• 'aborted': The operation was aborted, typically due to a concurrencyissue like transaction aborts, etc.
• 'out-of-range': Operation was attempted past the valid range.
• 'unimplemented': Operation is not implemented or not supported/enabled.
• 'internal': Internal errors. Means some invariants expected byunderlying system has been broken. If you see one of these errors,something is very broken.
• 'unavailable': The service is currently unavailable. This is most likelya transient condition and may be corrected by retrying with a backoff.
• 'data-loss': Unrecoverable data loss or corruption.
• 'unauthenticated': The request does not have valid authenticationcredentials for the operation.