random_uniform causes VM to crash

[marfago]

The code nd.random_uniform(3) crashes with

[19:51:29] /Users/travis/build/dmlc/mxnet-distro/mxnet-build/dmlc-core/include/dmlc/logging.h:308: [19:51:29] src/operator/random/./sample_op.h:294: Check failed: param.high >= param.low (1 vs. 3) low must be less or equal to high in uniform distribution

caused by

libc++abi.dylib: terminating with uncaught exception of type dmlc::Error: [19:51:29] src/engine/./threaded_engine.h:359: [19:51:29] src/operator/random/./sample_op.h:294: Check failed: param.high >= param.low (1 vs. 3) low must be less or equal to high in uniform distribution

Experienced with mxnet 1.0.0 on macOS Sierra and python 3.6.3

[reminisce]

In this case, low=3, high=1, raising an error is consistent with NumPy's random.uniform definition.

When high == low, values of low will be returned. If high < low, the results are officially undefined and may eventually raise an error, i.e. do not rely on this function to behave when passed arguments satisfying that inequality condition.

[marfago]

I think that crashing the VM because of wrong parameters should not be the right behavior. The expected one should be a python exception.

[reminisce]

Agree that crashing the vm is not a desired behavior. Need to add exception handling in frontend.

[eric-haibin-lin]

@anirudh2290 is working on general exception handling.

[marfago]

#9154

[anirudh2290]

#7335