Related #1387.  Connectors error messages are broken as well
![image](https://user-images.githubusercontent.com/1494347/151330767-32c21223-e5a7-447b-be65-7bccafcf6d09.png)
 Topic creation:
<img width="541" alt="image" src="https://user-images.githubusercontent.com/1494347/153438290-dfc64d0e-8cd6-4235-8ec5-4d16f2df39a3.png">

SR: Display a clear warning message if a schema already exists
### Is your proposal related to a problem?

<!--
  Provide a clear and concise description of what the problem is.
  For example, "I'm always frustrated when..."
-->

(Write your answer here.)
If you try to create a schema with a name that already exists now is displaying an unclear message (the same for already existing name, invalid syntax, incorrect schema`s type).

### Describe the solution you'd like

<!--
  Provide a clear and concise description of what you want to happen.
-->

(Describe your proposed solution here.)
Display a clear warning message what the problem is, i.e. for this case, 'There is already a schema with the name XXX'.
 
### Describe alternatives you've considered

<!--
  Let us know about other solutions you've tried or researched.
-->

(Write your answer here.)

### Additional context

<!--
  Is there anything else you can add about the proposal?
  You might want to link to related issues here, if you haven't already.
-->

(Write your answer here.)

kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts kafka-ui-react-app/src/redux/actions/thunks/connectors.ts
kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts kafka-ui-react-app/src/redux/actions/thunks/connectors.ts
diff --git a/kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts b/kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts
index c72e15653ad..aa20ed6313c 100644
--- a/kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts
+++ b/kafka-ui-react-app/src/redux/actions/__test__/thunks/connectors.spec.ts
@@ -192,7 +192,7 @@ describe('Thunks', () => {
         actions.createConnectorAction.failure({
           alert: {
             subject: 'local-first',
-            title: 'Kafka Connect Connector Create',
+            title: `Connector with name ${connectorName} already exists`,
             response: {
               status: 404,
               statusText: 'Not Found',
diff --git a/kafka-ui-react-app/src/redux/actions/thunks/connectors.ts b/kafka-ui-react-app/src/redux/actions/thunks/connectors.ts
index 35124e7ceb5..76aec393cec 100644
--- a/kafka-ui-react-app/src/redux/actions/thunks/connectors.ts
+++ b/kafka-ui-react-app/src/redux/actions/thunks/connectors.ts
@@ -111,7 +111,7 @@ export const createConnector =
       const response = await getResponse(error);
       const alert: FailurePayload = {
         subject: [clusterName, connectName].join('-'),
-        title: `Kafka Connect Connector Create`,
+        title: `Connector with name ${newConnector.name} already exists`,
         response,
       };
       dispatch(actions.createConnectorAction.failure({ alert }));
