chore: invalid syntax in the example code

[bananaumai]

About

• removed duplicated import statement
• fixed invalid assignment statement

Note

BTW, when I tries to run the example code for working with extension type, I have faced the following tsc compile error.

error TS2322: Type 'ExtensionCodec<MyContext>' is not assignable to type 'ExtensionCodecType<undefined>'.
  Types of property '__brand' are incompatible.
    Type 'MyContext' is not assignable to type 'undefined'.

I'm investigating the issue it right now. If there'll be something worth to be considered, I'll suggest another PR or raise up an issue.

[gfx]

Looks good to me. Thank you!

For the context trick in ExtensionCodec, see its test:

msgpack-javascript/test/ExtensionCodec.test.ts

Lines 101 to 132 in a6a5ddc

	context("custom extensions with custom context", () => {
	class Context {
	public expectations: Array<any> = [];
	constructor(public ctxVal: number) {}
	public hasVisited(val: any) {
	this.expectations.push(val);
	}
	}
	const extensionCodec = new ExtensionCodec<Context>();
	class Magic<T> {
	constructor(public val: T) {}
	}
	// Magic
	extensionCodec.register({
	type: 0,
	encode: (object: unknown, context): Uint8Array | null => {
	if (object instanceof Magic) {
	context.hasVisited({ encoding: object.val });
	return encode({ magic: object.val, ctx: context.ctxVal }, { extensionCodec, context });
	} else {
	return null;
	}
	},
	decode: (data: Uint8Array, extType, context) => {
	extType;
	const decoded = decode(data, { extensionCodec, context }) as { magic: number };
	context.hasVisited({ decoding: decoded.magic, ctx: context.ctxVal });
	return new Magic(decoded.magic);
	},
	});

[codecov-commenter]

Codecov Report

Merging #135 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #135   +/-   ##
=======================================
  Coverage   98.29%   98.29%           
=======================================
  Files          15       15           
  Lines         936      936           
  Branches      205      205           
=======================================
  Hits          920      920           
  Misses         16       16           

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