Fix docstring typo about Context class

[hassaku63]

Issue #, if available:

Description of changes:

This pull request corrects a typographical error in the docstring of the Context class, ensuring the documentation accurately reflects the intended message.

The current docstring for the Context class contains an incorrect repeated "if" which makes the sentence unclear.

I believe this is a typo, so I have corrected it to:

For any data access or data mutation, if there is no active segment present
it will use user-defined behavior to handle such case. By default it throws
an runtime error.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.