🎨 Centralize error throwing for encryption keys and credentials (#3105)

* Centralized error throwing for encryption key

* Unifying the error message used by cli and core packages

* Improvements to error messages to make it more DRY

* Removed unnecessary throw

* Throwing error when credential does not exist to simplify node behavior (#3112)

Co-authored-by: Iván Ovejero <ivov.src@gmail.com>

packages/workflow/test/Helpers.ts

@@ -211,7 +211,7 @@ export function getExecuteFunctions(
 			async getCredentials(
 				type: string,
 				itemIndex?: number,
-			): Promise<ICredentialDataDecryptedObject | undefined> {
+			): Promise<ICredentialDataDecryptedObject> {
 				return {
 					apiKey: '12345',
 				};
@@ -388,7 +388,7 @@ export function getExecuteSingleFunctions(
 			getContext(type: string): IContextObject {
 				return NodeHelpers.getContext(runExecutionData, type, node);
 			},
-			async getCredentials(type: string): Promise<ICredentialDataDecryptedObject | undefined> {
+			async getCredentials(type: string): Promise<ICredentialDataDecryptedObject> {
 				return {
 					apiKey: '12345',
 				};