Federated query validation error messages

[mpoffald]

• Adds some additional :error/messages to accommodate changes from Feature/federated queries #606
• updates Malli to a version that has a recent fix for an error utility fn we use
• Some errors since the schema change are showing up with nil values, this tweaks the logic used to extract the value so that the "Provided: <value>" portion of the error doesn't print nils

In general, as a consequence of expanding ::where-map by using a disjunction, some of our where clause errors aren't as specific as they could be. I have some ideas for how to fix that, but since fql schema is going to change again soon with new where syntax, it's better to hold off for now. This is just the low-hanging fruit that was available.

Examples of validation errors with these changes:

  ;; graph map  missing a where key
  (syntax/coerce-query '{"@context" "https://schema.org"
                         :from-named ["test/authors" "test/books" "test/movies"]
                         :select    [?movieName ?bookIsbn ?authorName]
                         :where     [{:graph "test/movies"}]})
;;=>
 ;; Error in value for "where"; where clauses must be valid tuples or maps;
 ;;  Invalid where map, must be either named graph or valid where operation map;
 ;;  Provided: {:graph "test/movies"}; See documentation for details:
 ;;  https://next.developers.flur.ee/docs/reference/errorcodes#query-invalid-where

  ;; graph map  w/ invalid where clause
  (syntax/coerce-query '{"@context" "https://schema.org"
                         :from-named ["test/authors" "test/books" "test/movies"]
                         :select    [?movieName ?bookIsbn ?authorName]
                         :where     [{:graph "test/authors"
                                      ;; invalid where
                                      :where [?author "name" ?authorName]}]})
;;=>
 ;;  Error in value for "where"; where clauses must be valid tuples or maps;
 ;;  Invalid where map, must be either named graph or valid where operation map;
 ;;  Provided: {:graph "test/authors", :where [?author "name" ?authorName]}; See
 ;;  documentation for details:
 ;;  https://next.developers.flur.ee/docs/reference/errorcodes#query-invalid-where
 

  ;;invalid value in `:from` vector
  (syntax/coerce-query '{"@context" "https://schema.org"
                         :from      [2]
                         :select    [?movieName ?bookIsbn ?authorName]
                         :where     [[?movie "type" "Movie"]
                                     [?movie "name" ?movieName]
                                     [?movie "isBasedOn" ?book]
                                     [?book "isbn" ?bookIsbn]
                                     [?book "author" ?author]
                                     [?author "name" ?authorName]]})
;;=>
 ;;  Error in value for "from"; invalid iri; Provided: 2; See documentation for
 ;;  details:
 ;;  https://next.developers.flur.ee/docs/reference/errorcodes#query-invalid-from

  ;;another invalid value for `:from`
  (syntax/coerce-query '{"@context" "https://schema.org"
                         :from      2
                         :select    [?movieName ?bookIsbn ?authorName]
                         :where     [[?movie "type" "Movie"]
                                     [?movie "name" ?movieName]
                                     [?movie "isBasedOn" ?book]
                                     [?book "isbn" ?bookIsbn]
                                     [?book "author" ?author]
                                     [?author "name" ?authorName]]})
;;=>
 ;;  Error in value for "from"; from must be a ledger iri or vector of ledger
 ;;  iris; Provided: 2; See documentation for details:
 ;;  https://next.developers.flur.ee/docs/reference/errorcodes#query-invalid-from


  ;; invalid value for `:graph` key:
  (syntax/coerce-query '{"@context" "https://schema.org"
                         :from-named ["test/authors" "test/books" "test/movies"]
                         :select    [?movieName ?bookIsbn ?authorName]
                         :where     [{:graph 2
                                      :where [[?movie "type" "Movie"]
                                              [?movie "name" ?movieName]
                                              [?movie "isBasedOn" ?book]]}]})
;;=>
 ;;  Error in value for "where"; Value of "graph" should be ledger alias or
 ;;  variable; Provided: 2; See documentation for details:
 ;;  https://next.developers.flur.ee/docs/reference/errorcodes#query-invalid-where

[cap10morgan]

One clarifying question but looks good overall