plugins: imap-filter-sieve: Make sure an (internal) error message is …

…available for failed compile.

src/plugins/imap-filter-sieve/imap-filter-sieve.c

@@ -433,7 +433,6 @@ int imap_filter_sieve_compile(struct imap_filter_sieve_context *sctx,
 				const char *errormsg =
 					sieve_script_get_last_error(
 						script, &error);
-
 				if (error != SIEVE_ERROR_NONE) {
 					str_truncate(sctx->errors, 0);
 					str_append(sctx->errors, errormsg);
@@ -444,6 +443,12 @@ int imap_filter_sieve_compile(struct imap_filter_sieve_context *sctx,
 		}
 	}
 
+	if (ret < 0 && str_len(sctx->errors) == 0) {
+		/* Failed, but no user error was logged: log a generic internal
+		   error instead. */
+		sieve_internal_error(ehandler, NULL, NULL);
+	}
+
 	*have_warnings_r = (sieve_get_warnings(ehandler) > 0);
 	*errors_r = sctx->errors;