[#121] added error handler and snackbar

src/components/Error/ErrorSnackbar.tsx

@@ -0,0 +1,38 @@
+import Snackbar from "@mui/material/Snackbar";
+import Alert from "@mui/material/Alert";
+import Button from "@mui/material/Button";
+
+interface Props {
+  messages: string[];
+  onClose: () => void;
+}
+
+export function EventErrorSnackbar({ messages, onClose }: Props) {
+  const open = messages.length > 0;
+  const summary =
+    messages.length === 1
+      ? messages[0]
+      : `${messages.length} events with errors`;
+
+  return (
+    <Snackbar
+      open={open}
+      autoHideDuration={6000}
+      onClose={onClose}
+      anchorOrigin={{ vertical: "bottom", horizontal: "center" }}
+    >
+      <Alert
+        severity="error"
+        onClose={onClose}
+        sx={{ width: "100%" }}
+        action={
+          <Button color="inherit" size="small" onClick={onClose}>
+            OK
+          </Button>
+        }
+      >
+        {summary}
+      </Alert>
+    </Snackbar>
+  );
+}

src/components/Error/EventErrorHandler.ts

@@ -0,0 +1,25 @@
+export class EventErrorHandler {
+  private errors = new Map<string, string>();
+  private onErrorCallback?: (messages: string[]) => void;
+
+  setErrorCallback(callback: (messages: string[]) => void) {
+    this.onErrorCallback = callback;
+  }
+
+  reportError(eventId: string, message: string) {
+    if (!this.errors.has(eventId)) {
+      this.errors.set(eventId, message);
+      console.warn(`[EventErrorHandler] ${eventId}: ${message}`);
+      this.emit();
+    }
+  }
+
+  clearAll() {
+    this.errors.clear();
+    this.emit();
+  }
+
+  private emit() {
+    this.onErrorCallback?.(Array.from(this.errors.values()));
+  }
+}