Reference

Error code reference

Every diagnostic the Super.js compiler can emit. Codes are permanent — never renumbered or reused. SJS-P are parser errors, SJS-E type errors, SJS-W warnings (promoted to errors in strict mode), and SJS-L lint rules.

55 codes, generated from the @superjs/diagnostics registry.

Parser

Code	Severity	Message	Stage
SJS-P001	error	Unexpected token	Stage 1
SJS-P002	error	Unexpected end of file	Stage 1
SJS-P003	error	Invalid syntax in type annotation	Stage 1
SJS-P004	error	Invalid sum type declaration	Stage 1
SJS-P005	error	Invalid match expression	Stage 1
SJS-P099	error	Too many parse errors; recovery abandoned	Stage 1

Null safety

Code	Severity	Message	Stage
SJS-E001	error	Null or undefined assigned to non-nullable type `{type}`	Stage 0
SJS-E003	error	Property access on possibly-null value	Stage 0
SJS-E011	error	Non-null assertion `!` is not allowed; use narrowing	Stage 1

Type checking

Code	Severity	Message	Stage
SJS-E002	error	Type mismatch: expected `{expected}`, found `{found}`	Stage 0
SJS-E004	error	`any` is not a valid type in SJS; use `dynamic`	Stage 1
SJS-E005	error	Intersection type `A & B` is not allowed; use interface extension	Stage 1
SJS-E006	error	Mapped type is not allowed in SJS	Stage 1
SJS-E008	error	Conditional type `T extends U ? A : B` is not allowed	Stage 1
SJS-E009	error	`infer` keyword is not allowed in SJS	Stage 1
SJS-E010	error	TypeScript `enum` is not allowed; use sum types	Stage 1
SJS-E012	error	`namespace` is not allowed; use ES modules	Stage 1
SJS-E020	error	Ambiguous variant constructor `{variant}` — multiple sum types declare it; annotate the expected type	Stage 1
SJS-W006	warning	Excess property `{name}` on a fresh object literal assigned to a typed position	Stage 1

Match expressions

Code	Severity	Message	Stage
SJS-E007	error	Match expression is not exhaustive: missing variant `{variant}`	Stage 0
SJS-W003	warning	Unreachable `match` arm — earlier arm already covers this variant	Stage 1

Control flow

Code	Severity	Message	Stage
SJS-E013	error	`with` statement not allowed (SJS is always strict mode)	Stage 1
SJS-W008	warning	Implicit switch fallthrough between non-empty case clauses	Stage 1
SJS-W009	warning	Unreachable code following a terminator statement	Stage 1

Access modifiers

Code	Severity	Message	Stage
SJS-E014	error	Member `{member}` is not accessible from this scope	Stage 1
SJS-E015	error	Cannot narrow an access modifier on an overriding member	Stage 1
SJS-W005	warning	Explicit `public` modifier is redundant — members are public by default	Stage 1

Classes

Code	Severity	Message	Stage
SJS-E016	error	Cannot instantiate an abstract class directly with `new`	Stage 1

Modules

Code	Severity	Message	Stage
SJS-E017	error	Circular import detected — module graph contains a cycle	Stage 1

Async / await

Code	Severity	Message	Stage
SJS-E018	error	Top-level `await` used outside an ES module context	Stage 1

JSX

Code	Severity	Message	Stage
SJS-E019	error	Unknown JSX element type `{name}`	Stage 2
SJS-W007	warning	Missing `key` prop on JSX element in a list or iterator context	Stage 2

Dynamic

Code	Severity	Message	Stage
SJS-W001	warning	Implicit `dynamic` — unannotated position in `--strict` mode	Stage 0
SJS-W002	warning	`dynamic` value assigned to a typed position without a narrowing check	Stage 1

Keywords

Code	Severity	Message	Stage
SJS-W004	warning	Reserved or future SJS keyword `{name}` used as an identifier	Stage 1

Try / catch

Code	Severity	Message	Stage
SJS-W010	warning	`catch` binding not typed as `Error` or `unknown`	Stage 1

Security

Code	Severity	Message	Stage
SJS-W012	warning	BiDi control character in source file	Stage 1
SJS-L011	error	BiDi control character rejected	Stage 1

Lint

Code	Severity	Message	Stage
SJS-L001	warning	Prefer `const` — `let` binding `{name}` is never reassigned	Stage 3
SJS-L002	warning	Prefer `let` or `const` over `var`	Stage 3
SJS-L003	warning	Use `===` / `!==` — `==` / `!=` performs type coercion	Stage 3
SJS-L004	warning	Prefer `for…of` over `for…in` for array and iterable iteration	Stage 3
SJS-L005	warning	`debugger` statement found in committed code	Stage 3
SJS-L006	warning	`match` expression has no arms	Stage 3
SJS-L007	warning	Redundant match arm — variant `{variant}` is already handled	Stage 3
SJS-L008	warning	Prefer an arrow function over a `function` expression callback	Stage 3
SJS-L009	warning	Unused import — `{name}` is never used	Stage 3
SJS-L010	warning	Import `{source}` is out of order — sort imports by source	Stage 3
SJS-L012	warning	Unused declaration — `{name}` is never used	Stage 3
SJS-L013	warning	Explicit `dynamic` type — annotate precisely, or add `// @sjs:dynamic-ok`	Stage 3
SJS-L014	warning	`{name}` shadows a binding from an enclosing scope	Stage 3
SJS-L015	warning	Floating promise — `await`, `return`, or otherwise consume this `Promise`	Stage 3
SJS-L016	warning	Unhandled `Result` — `match`, `return`, or otherwise consume it	Stage 3
SJS-L017	warning	Prefer returning `Result<T, E>` over `throw` (RFC-0004)	Stage 3
SJS-L018	warning	Mixed spaces and tabs in leading indentation	Stage 3