Fix gh env schema union issue

Author: myftija

apps/webapp/app/env.server.ts

@@ -4,21 +4,27 @@ import { isValidDatabaseUrl } from "./utils/db";
 import { isValidRegex } from "./utils/regex";
 
 const GithubAppEnvSchema = z
-  .discriminatedUnion("GITHUB_APP_ENABLED", [
-    z.object({
-      GITHUB_APP_ENABLED: z.literal("1"),
-      GITHUB_APP_ID: z.string(),
-      GITHUB_APP_PRIVATE_KEY: z.string(),
-      GITHUB_APP_WEBHOOK_SECRET: z.string(),
-      GITHUB_APP_SLUG: z.string(),
-    }),
-    z.object({
-      GITHUB_APP_ENABLED: z.literal("0"),
-    }),
-  ])
-  .default({
-    GITHUB_APP_ENABLED: "0",
-  });
+  .preprocess(
+    (val) => {
+      const obj = val as any;
+      if (!obj || !obj.GITHUB_APP_ENABLED) {
+        return { ...obj, GITHUB_APP_ENABLED: "0" };
+      }
+      return obj;
+    },
+    z.discriminatedUnion("GITHUB_APP_ENABLED", [
+      z.object({
+        GITHUB_APP_ENABLED: z.literal("1"),
+        GITHUB_APP_ID: z.string(),
+        GITHUB_APP_PRIVATE_KEY: z.string(),
+        GITHUB_APP_WEBHOOK_SECRET: z.string(),
+        GITHUB_APP_SLUG: z.string(),
+      }),
+      z.object({
+        GITHUB_APP_ENABLED: z.literal("0"),
+      }),
+    ])
+  );
 
 const EnvironmentSchema = z
   .object({