Polyline handle Google Directions API request exception without raise

[th3w4y]

Short Description:

handle IndexError in request response from the Google Directions API

Two cases are noticed:
a)
In case of API limit reached we get back we get a status 200 code with an empty routes []

{u'error_message': u'You have exceeded your rate-limit for this API.',
u'routes': [],
u'status': u'OVER_QUERY_LIMIT'
}

b) ZERO_RESULTS {
"geocoded_waypoints" : [ {}, {} ],
"routes" : [],
"status" : "ZERO_RESULTS"
}

Fixes/Resolves/Closes (please use correct syntax):

• poly line walker cause a problem, just started, then error. #5020
• handle exceptions inside the Polyline class
• does not raise to walker_factory or PolylineWalker
• has internal fallback behaviour similar with StepWalker, walking a geometrical walk in both a) and b) exception cases

[mention-bot]

@th3w4y, thanks for your PR! By analyzing the annotation information on this pull request, we identified @kanemasa1987, @solderzzc and @alexyaoyang to be potential reviewers

[solderzzc]

👍