fix: remove signature from store when delete returns 404

When attempting to delete a signature that no longer exists on the
server (404 response), the signature was not being removed from the
Pinia store, leaving stale data in the UI.

This fix checks for 404 status in the error handler and clears the
signature from the store, ensuring the UI state matches the server
state even when the signature was already deleted.

Also improved error handling to safely access nested response
properties and provide a fallback error message.

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/store/signatureElements.js

@@ -136,8 +136,11 @@ export const useSignatureElementsStore = function(...args) {
 						this.signs[type] = emptyElement
 						this.success = data.ocs.data.message
 					})
-					.catch(({ data }) => {
-						this.error = { message: data.ocs.data.message }
+					.catch(({ response }) => {
+						if (response?.status === 404) {
+							this.signs[type] = emptyElement
+						}
+						this.error = { message: response?.data?.ocs?.data?.message || 'Error deleting signature' }
 					})
 			},
 		},