Unhashable type: 'dict' with paired t-test chart

[ghost]

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.

Superset version

0.29.0rc7 (latest pypi version)

Expected results

Chart should display the results correctly.

Actual results

I'm getting the following error if not count(*) metric is used.

I can see this error message in the logs

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/superset/views/base.py", line 96, in wraps
    return f(self, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/superset/views/core.py", line 1211, in explore_json
    samples=samples,
  File "/usr/local/lib/python3.6/site-packages/superset/views/core.py", line 1142, in generate_json
    payload = viz_obj.get_payload()
  File "/usr/local/lib/python3.6/site-packages/superset/viz.py", line 374, in get_payload
    payload['data'] = self.get_data(df)
  File "/usr/local/lib/python3.6/site-packages/superset/viz.py", line 2532, in get_data
    values=metrics)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/frame.py", line 5303, in pivot_table
    margins_name=margins_name)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/reshape/pivot.py", line 60, in pivot_table
    if i not in data:
  File "/usr/local/lib/python3.6/site-packages/pandas/core/generic.py", line 1519, in __contains__
    return key in self._info_axis
  File "/usr/local/lib/python3.6/site-packages/pandas/core/indexes/base.py", line 2021, in __contains__
    hash(key)
TypeError: unhashable type: 'dict'

Steps to reproduce

• Install superset, load sample data as given in the installation guide
• Create a paired t-test chart with any source and choose any metric except count(*)
• Run Query

[ghost]

Hi. Sorry for the late response. I checked your fix and although now this error is fixed, it generates a new one which seems to be frontend related.

I checked the logs and I can see the following error message:

Uncaught TypeError: Cannot read property 'map' of undefined
    at ProxyComponent.o [as render] (webpack-internal:///./node_modules/@superset-ui/legacy-plugin-chart-paired-t-test/esm/TTestTable.js:36)
    at ProxyComponent.hotComponentRender (webpack-internal:///./node_modules/react-hot-loader/dist/react-hot-loader.development.js:728)
    at ProxyComponent.proxiedRender (webpack-internal:///./node_modules/react-hot-loader/dist/react-hot-loader.development.js:748)
    at finishClassComponent (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:14301)
    at updateClassComponent (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:14264)
    at beginWork (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:15082)
    at performUnitOfWork (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:17820)
    at workLoop (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:17860)
    at HTMLUnknownElement.callCallback (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:149)
    at Object.invokeGuardedCallbackDev (webpack-internal:///./node_modules/react-dom/cjs/react-dom.development.js:199)

Do you have any idea what can cause this issue?