Hotfix/error messages

.docker/docker-compose.yml

.docs/api/gateway-service.md

...ice/src/main/java/at/tuwien/endpoints/SubsetEndpoint.java

...vice/src/main/java/at/tuwien/endpoints/TableEndpoint.java

...rvice/src/main/java/at/tuwien/endpoints/ViewEndpoint.java

.../test/java/at/tuwien/endpoint/SubsetEndpointUnitTest.java

...c/test/java/at/tuwien/endpoint/TableEndpointUnitTest.java

...rc/test/java/at/tuwien/endpoint/ViewEndpointUnitTest.java

...rc/test/java/at/tuwien/mvc/PrometheusEndpointMvcTest.java

...e/services/src/main/java/at/tuwien/mapper/DataMapper.java

.../java/at/tuwien/service/impl/TableServiceMariaDbImpl.java

dbrepo-gateway-service/dbrepo.conf

dbrepo-ui/components/database/DatabaseCard.vue

dbrepo-ui/components/database/DatabaseToolbar.vue

dbrepo-ui/components/identifier/Citation.vue

dbrepo-ui/components/subset/SubsetList.vue

dbrepo-ui/components/subset/SubsetToolbar.vue

dbrepo-ui/components/view/ViewToolbar.vue

dbrepo-ui/composables/axios-instance.ts

dbrepo-ui/composables/identifier-service.ts