Report Failures more Elegantly

[mmcky]

Currently failures are reported within ipynb formatting

distributed.worker - WARNING -  Compute Failed
Function:  preprocess
args:      ({'cells': [{'cell_type': 'markdown', 'metadata': {}, 'source': '\n<a id=\'lqramsey\'></a>\n<div id="qe-notebook-header" style="text-align:right;">\n        <a href="https://quantecon.org/" title="quantecon.org">\n                <img style="width:250px;display:inline;" src="https://assets.quantecon.org/img/qe-menubar-logo.svg" alt="QuantEcon">\n        </a>\n</div>'}, {'cell_type': 'markdown', 'metadata': {}, 'source': "# Optimal Taxation in an LQ Economy\n\n\n<a id='index-1'></a>"}, {'cell_type': 'markdown', 'metadata': {}, 'source': '## Contents\n\n- [Optimal Taxation in an LQ Economy](#Optimal-Taxation-in-an-LQ-Economy)  \n  - [Overview](#Overview)  \n  - [The Ramsey Problem](#The-Ramsey-Problem)  \n  - [Implementation](#Implementation)  \n  - [Examples](#Examples)  \n  - [Exercises](#Exercises)  \n  - [Solutions](#Solutions)  '}, {'cell_type': 'markdown', 'metadata': {}, 'source': '## Overview\n\nIn this lecture we study optimal fiscal policy in a linear quadratic setting\n\nWe sl
kwargs:    {}
Exception: CellExecutionError('An error occurred while executing the following cell:\n------------------\nusing InstantiateFromURL\ngithub_project("QuantEcon/quantecon-notebooks-jl", version = "v0.9.10");\n# ] instantiate  # uncomment if required\n------------------\n\nUndefVarError: github_project not defined\n\nStacktrace:\n [1] top-level scope at In[1]:2\nUndefVarError: UndefVarError: github_project not defined\n')

(22/77)  dynamic_programming_squared/lqramsey -- fail -- 16.05s

we should unwrap these and report the actual Traceback for more informative messages.