fix typo in error message (#3161)

Author: clenfest

composition-js/src/__tests__/compose.setContext.test.ts

@@ -817,7 +817,7 @@ describe("setContext tests", () => {
     expect(result.schema).toBeUndefined();
     expect(result.errors?.length).toBe(1);
     expect(result.errors?.[0].message).toBe(
-      '[Subgraph1] Object "U" has no resolvable key but has an a field with a contextual argument.'
+      '[Subgraph1] Object "U" has no resolvable key but has a field with a contextual argument.'
     );
   });
 

internals-js/src/federation.ts

@@ -1808,7 +1808,7 @@ export class FederationBlueprint extends SchemaBlueprint {
         const keyApplications = objectType.appliedDirectivesOf(keyDirective);
         if (!keyApplications.some(app => app.arguments().resolvable || app.arguments().resolvable === undefined)) {
           errorCollector.push(ERRORS.CONTEXT_NO_RESOLVABLE_KEY.err(
-            `Object "${objectType.coordinate}" has no resolvable key but has an a field with a contextual argument.`,
+            `Object "${objectType.coordinate}" has no resolvable key but has a field with a contextual argument.`,
             { nodes: sourceASTs(objectType) }
           ));
         }