Improve 'No more mocked responses' error message

[Msordet]

Improves the error message when no more mocked responses are found.

2nd commit addressing: #6771

Example from tests:

Error: No more mocked responses for the query: query GetUser($username: String!) {
  user(username: $username) {
    id
    __typename
  }
}

Expected variables:
  {"username":"mock_username","age":"undefined"}
Found 1 mock with variables:
  1: {"username":"mock_username"}

Error: No more mocked responses for the query: query GetUser($username: String!) {
  user(username: $username) {
    id
    __typename
  }
}

Expected variables:
  {"username":"some_user","age":42}
Found 1 mock with variables:
  1: {"age":13,"username":"some_user"}

Error: No more mocked responses for the query: query GetUser($username: String!) {
  user(username: $username) {
    id
    __typename
  }
}

Expected variables:
  {"username":"mock_username"}

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

[apollo-cla]

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[lbartroli]

@Msordet what's the status of this?

[AnasMostefaoui]

Thank you for this suggestion it will help a lot figuring out the mismatch. is there any update on this PR ?

[dannycochran]

@benjamn anyway you can help bring this home? seems like some simple merge conflicts.

it's pretty tricky to debug mock mismatching at the moment.

[benjamn]

@dannycochran These changes should be available now in @apollo/client@3.4.0-rc.6, thanks to @markneub's PR #8340. Thanks for bringing this PR back to our attention.