src/vs/editor/common/model/textModel.ts/TextModel/getLineContent
class TextModel:	public getLineContent(lineNumber: number): string {
		this._assertNotDisposed();
		if (lineNumber < 1 || lineNumber > this.getLineCount()) {
			throw new Error('Illegal value for lineNumber');
		}

		return this._buffer.getLineContent(lineNumber);
	}