fixes

web/src/pages/import_export/import/logic.rs

@@ -489,7 +489,7 @@ fn reject(headers: &HeaderMap, message: String) -> Response {
 /// pattern a value does not satisfy — is the user's to fix and answers 422;
 /// only an actually unreachable backend answers 502.
 fn grpc_error(headers: &HeaderMap, error: &tonic::Status) -> Response {
-    crate::ui::FormError::from_status(error)
+    crate::ui::FormError::from_status_with_message(error, format!("{error:?}"))
         .into_response(Locale::from_headers(headers), ui::render_error)
 }
 
@@ -509,13 +509,14 @@ fn import_error(
         return failure.into_response(locale, ui::render_error);
     }
     let status = failure.status_code();
+    let backend_error = format!("{error:?}");
     let message = ui::render_import_failure(
         locale,
         inserted_before_chunk + inserted_in_chunk,
         prepared_rows,
         // One header row precedes the data, and CSV rows are one-based.
         chunk_start + failed_row_index + 2,
-        failure.message(),
+        &backend_error,
     );
     (status, Html(message)).into_response()
 }