refactor: Removes unnecessary DispatchQueue

This is unnecessary because we only ever write the property in its entirety without appending or modifying it in any way. This change may cause us to validate the schema multiple times concurrently early in our start up process, (which should end up with the same result), but the code simplification seems worth it.

Author: NeedleInAJayStack

Sources/GraphQL/Type/Schema.swift

@@ -34,26 +34,9 @@ public final class GraphQLSchema: @unchecked Sendable {
     let astNode: SchemaDefinition?
     let extensionASTNodes: [SchemaExtensionDefinition]
 
-    // Used as a cache for validateSchema().
-    private var _validationErrors: [GraphQLError]?
-    private let validationErrorQueue = DispatchQueue(
-        label: "graphql.schema.validationerrors",
-        attributes: .concurrent
-    )
-    var validationErrors: [GraphQLError]? {
-        get {
-            // Reads can occur concurrently.
-            return validationErrorQueue.sync {
-                _validationErrors
-            }
-        }
-        set {
-            // Writes occur sequentially.
-            return validationErrorQueue.sync(flags: .barrier) {
-                self._validationErrors = newValue
-            }
-        }
-    }
+    /// Used as a cache for validateSchema(). Concurrent access is not protected, so assume
+    /// it can be changed at any time.
+    var validationErrors: [GraphQLError]?
 
     public let queryType: GraphQLObjectType?
     public let mutationType: GraphQLObjectType?
@@ -95,7 +78,7 @@ public final class GraphQLSchema: @unchecked Sendable {
         extensionASTNodes: [SchemaExtensionDefinition] = [],
         assumeValid: Bool = false
     ) throws {
-        _validationErrors = assumeValid ? [] : nil
+        validationErrors = assumeValid ? [] : nil
 
         self.description = description
         self.extensions = extensions