Truncating Invalid Error Paths (PR #6359)
This fix addresses an issue where the router was silently dropping subgraph errors that included invalid paths.
According to the GraphQL Specification an error path must point to a response field:
If an error can be associated to a particular field in the GraphQL result, it must contain an entry with the key path that details the path of the response field which experienced the error.
If a subgraph error includes a path that can't be matched to a response field, the router now truncates the path to the nearest valid field path.
By @IvanGoncharov in #6359