Added tracebacks in py error messages

[terrytangyuan]

For more detailed error messages, e.g. the following message could at least tell you the shape does not match between the model you are building and the model saved previously.

Error in py_call(attrib, args, keywords) : 
  InvalidArgumentError: Shape in shape_and_slice spec does not match the shape in the save file: [11,3], save file shape: [10,3]
	 [[Node: save/restore_slice_23 = RestoreSlice[dt=DT_FLOAT, preferred_shard=0, _device="/job:localhost/replica:0/task:0/cpu:0"](_recv_save/Const_0, save/restore_slice_23/tensor_name, save/restore_slice_23/shape_and_slice)]]

Caused by op u'save/restore_slice_23', defined at:
  File "/usr/local/opt/python/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/tensorflow/contrib/learn/python/learn/estimators/dnn.py", line 435, in fit
    max_steps=max_steps)
  File "/usr/local/opt/python/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 333, in fit
    max_steps=max_steps)
  File "/usr/local/opt/python/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/tensorflow/contrib/learn/python/learn/estimators/estimator.py", line 708, in _train_

Originally, it was very obscure:

Error in py_call(attrib, args, keywords) : basic_string::_M_replace_aux

Issue reported in #40

[ShantanuKumar]

I get different error messages now in Rstudio terminal and unix terminal. Unix terminal has the improved error message, but Rstudio still shows the obscure error message.

[terrytangyuan]

Could you paste both versions of error messages?

[ShantanuKumar]

Sorry for the delay! Here are the two versions of error message:
Unix terminal: Error in py_call(attrib, args, keywords) : Unable to convert R object to python type Calls: <Anonymous> -> py_call -> .Call Execution halted

RStudio: Error in py_call(attrib, args, keywords) : basic_string::_M_replace_aux

[terrytangyuan]

It should be much better now. Try the most recent version

[pourzanj]

I'm using version 0.3.0, but I still don't get detailed error output. Any ideas?