implemented basic search function with Homebox provider

backend/src/main/java/com/vaessl/app/exception/ConnectionNotFoundException.java

@@ -0,0 +1,4 @@
+package com.vaessl.app.exception;
+
+public class ConnectionNotFoundException extends RuntimeException {
+}

backend/src/main/java/com/vaessl/app/exception/ErrorMessage.java

@@ -11,7 +11,12 @@ public enum ErrorMessage {
                             HttpStatus.SERVICE_UNAVAILABLE,
                             "The target URL is unreachable."), SERVER_ERROR_GENERAL(
                                     "The external app returned a server error: "), WRONG_SERVICE_TYPE(
-                                            HttpStatus.NOT_FOUND, "No such service type.");
+                                            HttpStatus.NOT_FOUND,
+                                            "No such service type."), CONNECTION_NOT_FOUND(
+                                                    HttpStatus.NOT_FOUND,
+                                                    "No active connection found for this service."), REMOTE_API_EMPTY_RESPONSE(
+                                                            HttpStatus.BAD_GATEWAY,
+                                                            "Remote API returned empty response for ");
 
     private final HttpStatus status;
     private final String message;

backend/src/main/java/com/vaessl/app/exception/GlobalExceptionHandler.java

@@ -59,6 +59,11 @@ public class GlobalExceptionHandler {
                 BAD_REQUEST_EMPTY_FIELDS.getMessage() + " " + e.getMissingFields());
     }
 
+    @ExceptionHandler(ConnectionNotFoundException.class)
+    public ProblemDetail handleConnectionNotFound(ConnectionNotFoundException e) {
+        return ProblemDetail.forStatusAndDetail(CONNECTION_NOT_FOUND.getStatus(), CONNECTION_NOT_FOUND.getMessage());
+    }
+
     @ExceptionHandler(RemoteApiException.class)
     public ProblemDetail handleRemoteApiException(RemoteApiException e) {
         return ProblemDetail.forStatusAndDetail(REMOTE_API_EMPTY_RESPONSE.getStatus(),