Apply suggestion from @renetapopova

Co-authored-by: Reneta Popova <[email protected]>

Author: hvub

modules/ROOT/pages/errors/gql-errors/42NAB.adoc

@@ -19,7 +19,7 @@ An error will be thrown with GQLSTATUS 42NAB and the following status descriptio
 
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-error: syntax error or access rule violation - not supported standalone call. WHERE is not supported in standalone call. Use `CALL ... YIELD ... WHERE ... RETURN ...` instead.
+error: syntax error or access rule violation - not supported standalone call. WHERE is not supported in a standalone call. Use `CALL ... YIELD ... WHERE ... RETURN ...` instead.
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 == Possible solutions