Custom 500 page

Also closes #329

pages/500.tsx

@@ -0,0 +1,22 @@
+import { Box, Flex, Heading } from "@chakra-ui/layout";
+import MyLink from "components/common/MyLink";
+import { useMyTheme } from "hooks/common";
+import Image from "next/image";
+
+const Custom500Page = () => {
+  const { gray } = useMyTheme();
+  return (
+    <Flex flexDirection="column" justifyContent="center" alignItems="center">
+      <Image src={`/layout/errorGirl.png`} width={584} height={487} />
+      <Heading>500 - Server-side error occurred</Heading>
+      <Box color={gray}>
+        For assistance please visit our{" "}
+        <MyLink href="https://discord.gg/sendou" isExternal>
+          Discord
+        </MyLink>
+      </Box>
+    </Flex>
+  );
+};
+
+export default Custom500Page;