Throw errors for incorrect mappings of graphType, fnType and sampler

[mauriciopoppe]

It's possible to send combinations of graphType, fnType and sampler that are invalid e.g.

• ERROR Error: implicit is not supported in the builtIn sampler #214
• Issues with closed path when used with sampler:'builtIn' (math.js) and graphType: 'polyline' #249 (comment)

[stale]

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