fix: add check for resetQueryStoreErrors in afterExecute

[shomukai]

Add a check for resetQueryStoreErrors.

The resetQueryStoreErrors function is in query's prototype, in theory it should not be undefined. But we encountered a case where resetQueryStoreErrors is undefined after some network error.
So got an error like:

TypeError: t.currentObservable.query.resetQueryStoreErrors is not a function

Still chasing what caused it.
As a quick fix, just added a check for resetQueryStoreErrors.

Please close this pull request, if not related.
Thanks.
And thanks for your time in advance.

We are using these versions:
@apollo/react-hooks 3.1.1
apollo-client 2.6.4
react-apollo 3.1.1
apollo-link 1.2.13
apollo-link-http 1.5.16
apollo-link-http-common 0.2.15
apollo-link-retry 2.2.15
apollo-utilities 1.3.2

Checklist:

• If this PR is a new feature, please reference an issue where a consensus about the design was reached (not necessary for small changes)
• Make sure all of the significant new logic is covered by tests
• If this was a change that affects the external API used in GitHunt-React, update GitHunt-React and post a link to the PR in the discussion.

[apollo-cla]

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