fix: render error messages for invalid templates (#3088)

Currently direct templates can be created without the required
signatures fields for signers.

This means that the document can be fully signed by everyone but will
ultimately fail the sealing step which leaves the document in an
unrecoverable state.

apps/remix/app/components/general/envelope-editor/envelope-editor-invalid-direct-template-alert.tsx

@@ -0,0 +1,55 @@
+import { useCurrentEnvelopeEditor } from '@documenso/lib/client-only/providers/envelope-editor-provider';
+import { getRecipientsWithMissingFields } from '@documenso/lib/utils/recipients';
+import { cn } from '@documenso/ui/lib/utils';
+import { Alert, AlertDescription, AlertTitle } from '@documenso/ui/primitives/alert';
+import { Trans } from '@lingui/react/macro';
+import { useMemo } from 'react';
+
+export type EnvelopeEditorInvalidDirectTemplateAlertProps = {
+  className?: string;
+};
+
+/**
+ * Warns that a direct link template cannot be used because one or more signers
+ * are missing a signature field.
+ */
+export const EnvelopeEditorInvalidDirectTemplateAlert = ({
+  className,
+}: EnvelopeEditorInvalidDirectTemplateAlertProps) => {
+  const { envelope, isTemplate } = useCurrentEnvelopeEditor();
+
+  const signersMissingSignatureFields = useMemo(() => {
+    if (!isTemplate || !envelope.directLink?.enabled) {
+      return [];
+    }
+
+    return getRecipientsWithMissingFields(envelope.recipients, envelope.fields);
+  }, [isTemplate, envelope.directLink, envelope.recipients, envelope.fields]);
+
+  if (signersMissingSignatureFields.length === 0) {
+    return null;
+  }
+
+  return (
+    <Alert
+      variant="destructive"
+      className={cn('mx-auto w-full max-w-[800px] flex-row items-start gap-3 rounded-sm', className)}
+    >
+      <AlertTitle>
+        <Trans>Invalid direct link template</Trans>
+      </AlertTitle>
+
+      <AlertDescription>
+        <Trans>
+          Recipients cannot use this direct link template because the following signers are missing a signature field
+        </Trans>
+
+        <ul className="list-disc pl-5">
+          {signersMissingSignatureFields.map((recipient, i) => (
+            <li key={recipient.id}>{recipient.email || recipient.name || `Recipient ${i + 1}`}</li>
+          ))}
+        </ul>
+      </AlertDescription>
+    </Alert>
+  );
+};