FuelLabs/fuels-ts · error · FuelError

TYPE_NOT_SUPPORTED

TYPE_NOT_SUPPORTED

Error message

Invalid number type: ${baseType}

What it means

Thrown inside NumberCoder's getLength helper (constructor path) when baseType is not 'u8', 'u16', or 'u32'. Message: "Invalid number type: <baseType>". Code is TYPE_NOT_SUPPORTED. NumberCoderType is a TypeScript union, so at the type level this is unreachable — it fires only when a non-union string reaches the constructor at runtime (e.g. via 'as any', a cast, or a dynamically-built type string).

Source

Thrown at packages/abi-coder/src/encoding/coders/NumberCoder.ts:20

import { toNumber, toBytes } from '@fuel-ts/math';

import type { EncodingOptions } from '../../types/EncodingOptions';
import { WORD_SIZE } from '../../utils/constants';

import { Coder } from './AbstractCoder';

type NumberCoderType = 'u8' | 'u16' | 'u32';

const getLength = (baseType: NumberCoderType): number => {
  switch (baseType) {
    case 'u8':
      return 1;
    case 'u16':
      return 2;
    case 'u32':
      return 4;
    default:
      throw new FuelError(ErrorCode.TYPE_NOT_SUPPORTED, `Invalid number type: ${baseType}`);
  }
};

export class NumberCoder extends Coder<number, number> {
  baseType: NumberCoderType;
  options: EncodingOptions;

  constructor(
    baseType: NumberCoderType,
    options: EncodingOptions = {
      padToWordSize: false,
    }
  ) {
    const length = options.padToWordSize ? WORD_SIZE : getLength(baseType);
    super('number', baseType, length);
    this.baseType = baseType;
    this.options = options;
  }

View on GitHub (pinned to b3f37c91ac)

Solutions

1. Use NumberCoder only for u8, u16, or u32; use BigNumberCoder for u64 and u256.
2. If you build coders from type strings, route u64/u256 to BigNumberCoder explicitly.
3. Constrain the baseType at the type level and avoid 'as any' casts.

Example fix

// before
new NumberCoder('u64') // u64 is not a NumberCoder type

// after
import { BigNumberCoder } from './BigNumberCoder'
new BigNumberCoder('u64') // correct coder for u64

const NUMBER_TYPES = new Set(['u8', 'u16', 'u32'])
if (!NUMBER_TYPES.has(baseType)) throw new Error(`use BigNumberCoder for ${baseType}`)
new NumberCoder(baseType as 'u8' | 'u16' | 'u32')

const isNumberCoderType = (t: string): t is 'u8' | 'u16' | 'u32' =>
  t === 'u8' || t === 'u16' || t === 'u32'

try { new NumberCoder(baseType as any) }
catch (e) { if ((e as FuelError).code === ErrorCode.TYPE_NOT_SUPPORTED) { /* route u64/u256 to BigNumberCoder */ } throw e }

When it happens

Trigger: Constructing new NumberCoder('u64') or any string other than u8/u16/u32 — most commonly passing 'u64'/'u256' (which belong to BigNumberCoder) or a malformed type token. Also reachable by casting arbitrary strings through 'as NumberCoderType' or building types dynamically.

Common situations: Confusing NumberCoder (u8/u16/u32) with BigNumberCoder (u64/u256); auto-generating coders from type strings without filtering; old code that assumed a wider set; a typo in the baseType literal.

Related errors

• ENCODE_ERROR
• ABI_TYPES_AND_VALUES_MISMATCH
• ENCODE_ERROR
• ENCODE_ERROR
• ENCODE_ERROR

AI-assisted analysis of FuelLabs/fuels-ts@b3f37c91ac (2026-08-12). Data as JSON: /api/errors/0b271492c83368aa. Report an issue: GitHub.