Exception Uncaught Can't access data until binding complete on method call when element list is empty

[techfg]

Describe the bug
When some APIs are invoked with an empty element list, an exception Uncaught Can't access data until binding complete is encountered.

To Reproduce
Steps to reproduce the behavior:

1. Open tooltips example
2. Execute any of the following:

$('fakeimg').mapster('get', 'bar');
$('fakeimg').mapster('keys', 'bar');

3. Exception Uncaught Can't access data until binding complete

Expected behavior
Operation should return a more meaningful message in this case since mapster has not been initialized on the image. If mapster is in the process of initializing, the error is accurate.

Screenshots
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Desktop (please complete the following information):
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Smartphone (please complete the following information):
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Additional context
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