Error Reference

Complete reference of all checker errors, runtime errors, and HTTP status codes returned by Grove.

What you'll learn: Every error Grove can produce, organized by category.

Checker Errors

Checker errors are caught at compile time by grove-cli check.

Code	Error	Description
`E0112`	Missing `kind` on root record	Root `record { ... }` has no `kind "xxx"` declaration as its first body item
`E0113`	`kind` on non-root record	`kind` declaration used on a named or child (`@parent(...)`) record, where it is forbidden
`E0114`	Invalid `kind` value	`kind` must be 2-5 lowercase ASCII letters, cannot start with `mz`, cannot be a reserved word
—	Multiple record declarations	Module has more than one root `record` block
—	Unknown type reference	A type name used in a field declaration is not defined
—	Unknown validate reference	An action references a validate that doesn't exist
—	Unknown event reference	An emit statement references an event that doesn't exist
—	Duplicate declaration name	Two declarations with the same name in the same module
—	Reserved field name	Field uses a reserved name: `pk`, `id`, `version`, `created_at`, `updated_at`, `created_by`, `updated_by`

Error	Description
Type mismatch	Expression type doesn't match expected type
Value type in user field	`Value` type used in record, event, or action field (only allowed at system boundaries)
Non-optional used as optional	Accessing `.field` on a non-optional value with `?.`
Unknown field access	Accessing a field that doesn't exist on the type

Error	Description
Emit outside action apply	`emit` used outside of an action's apply block
Emit in lambda	`emit` used inside a lambda expression
For loop outside action apply	`for` loop used outside of action apply
For loop nesting exceeded	`for` loops nested more than 3 levels deep
Let reassignment	Attempting to reassign an immutable `let` binding
Non-boolean validate body	Validate block expression doesn't return boolean
Non-boolean invariant body	Invariant expression doesn't return boolean

Error	Description
Invalid state transition	Event would cause a state transition not declared in the state machine
Unknown event in transition	State machine references an event that doesn't exist
Duplicate transition	Same from-state and event combination declared twice

Error	Description
Upcast version ordering	Source version is not lower than target version
Duplicate version	Same version tag on two declarations of the same name
Missing upcast	Version gap without an upcast to bridge it

Error	Description
Non-importable construct	Attempting to use imported module for non-importable constructs (aggregates, workflows, triggers, etc.)
Ambiguous type reference	Two imports define the same type name and it's used unqualified
Import not found	Import path doesn't resolve to a valid module

Runtime errors occur during action execution (grove-cli run or grove-server).

Error	Code	Description
Action not found	`ACTION_NOT_FOUND`	Request names an action that doesn't exist
Validation failed	`VALIDATION_FAILED`	A validate block returned false
Invariant violated	`INVARIANT_VIOLATED`	Record state after event application violates an invariant
State transition rejected	`STATE_TRANSITION_REJECTED`	Event would cause an invalid state transition
Record not found	`RECORD_NOT_FOUND`	Non-create action called for an entity that doesn't exist
Record already exists	`RECORD_EXISTS`	`@create` action called for an entity that already exists
Record deleted	`RECORD_DELETED`	Action called on a soft-deleted record
Event too large	`Z4004`	Event payload exceeds the 256 KiB per-event limit. See Limitations — Event payload size.

When using grove-server, errors map to HTTP status codes:

Status	When
`200 OK`	Action executed successfully
`400 Bad Request`	Validation failed, missing required fields
`404 Not Found`	Action or record not found
`409 Conflict`	State transition rejected, record already exists
`413 Payload Too Large`	Event payload exceeds the 256 KiB cap (code `Z4004`)
`422 Unprocessable Entity`	Invariant violated
`500 Internal Server Error`	Unexpected runtime error