Check AbstractInt bitLength on construction (#1902)

* Check AbstractInt bitLength on construction

* Language cleanups

packages/types/src/codec/AbstractInt.ts

@@ -6,7 +6,7 @@ import { H256 } from '../interfaces/runtime';
 import { AnyNumber, Codec, Registry } from '../types';
 
 import BN from 'bn.js';
-import { bnToBn, formatNumber, hexToBn, isHex, isString, isU8a, u8aToBn } from '@polkadot/util';
+import { assert, bnToBn, formatNumber, hexToBn, isHex, isString, isU8a, u8aToBn } from '@polkadot/util';
 import { blake2AsU8a } from '@polkadot/util-crypto';
 
 import Raw from './Raw';
@@ -38,6 +38,8 @@ export default abstract class AbstractInt extends BN implements Codec {
     this._bitLength = bitLength;
     this._isHexJson = isHexJson;
     this._isNegative = isNegative;
+
+    assert(super.bitLength() <= bitLength, `${this.toRawType()}: Input too large. Found input with ${super.bitLength()} bits, expected ${bitLength}`);
   }
 
   /** @internal */

packages/types/src/codec/UInt.spec.ts

@@ -10,6 +10,12 @@ import UInt from './UInt';
 describe('UInt', (): void => {
   const registry = new TypeRegistry();
 
+  it('fails on a number that is too large for the bits specified', (): void => {
+    expect(
+      (): UInt => new UInt(registry, '12345678901234567890123456789012345678901234567890', 32)
+    ).toThrow('u32: Input too large. Found input with 164 bits, expected 32');
+  });
+
   it('provides a toBn interface', (): void => {
     expect(
       new UInt(registry, 987).toBn().toNumber()