Method onWritable

tools/xsbug/esptool.js:473–483

(count)

				baud,
				device: this.#device,
				onWritable(count) {
					if (resolve)
						resolve(true);
					resolve = reject = undefined;

					this.flash.#writeSpaceAvailable = count;
					if (this.flash.#writable) {
						this.flash.#writable(true);
						this.flash.#writable = undefined;
					}
				},
				onReadable() {
					if (this.flash.#readable) {
						this.flash.#readable(true);