fix: delta stream parser

[jczhong84]

Previously when the stream ends with non-empty buffer, the data in the buffer will not be flushed to the final result.

[czgu]

I am a bit iffy about having mutation in getter. What about just rename this to ?

public close() { ... }

then at the end you do:

parser.close();
onStreamingEnd?.(parser.result);

also change result into a getter like

public get result() { return {...this._result} }

then the parse code can be:

parser.parse(delta);
onStreaming(parser.result);