diff --git a/app/api/__generated__/msw-handlers.ts b/app/api/__generated__/msw-handlers.ts
index 9f698776e6..a91f95b231 100644
--- a/app/api/__generated__/msw-handlers.ts
+++ b/app/api/__generated__/msw-handlers.ts
@@ -1341,9 +1341,10 @@ function validateParams<S extends ZodSchema>(
 
   // if any of the errors come from path params, just 404 — the resource cannot
   // exist if there's no valid name
-  const { issues } = result.error
-  const status = issues.some((e) => e.path[0] === 'path') ? 404 : 400
-  return { paramsErr: json(issues, { status }) }
+  const status = result.error.issues.some((e) => e.path[0] === 'path') ? 404 : 400
+  const error_code = status === 404 ? 'NotFound' : 'InvalidRequest'
+  const message = 'Zod error for params: ' + JSON.stringify(result.error)
+  return { paramsErr: json({ error_code, message }, { status }) }
 }
 
 const handler =
@@ -1364,7 +1365,7 @@ const handler =
     const { params, paramsErr } = paramSchema
       ? validateParams(paramSchema, req, pathParams)
       : { params: {}, paramsErr: undefined }
-    if (paramsErr) return json(paramsErr, { status: 400 })
+    if (paramsErr) return paramsErr
 
     const { path, query } = params
 
@@ -1372,7 +1373,10 @@ const handler =
     if (bodySchema) {
       const rawBody = await req.json()
       const result = bodySchema.transform(snakeify).safeParse(rawBody)
-      if (!result.success) return json(result.error.issues, { status: 400 })
+      if (!result.success) {
+        const message = 'Zod error for body: ' + JSON.stringify(result.error)
+        return json({ error_code: 'InvalidRequest', message }, { status: 400 })
+      }
       body = result.data
     }
 
@@ -1387,9 +1391,6 @@ const handler =
       if (typeof result === 'number') {
         return new HttpResponse(null, { status: result })
       }
-      if (typeof result === 'function') {
-        return result()
-      }
       if (result instanceof Response) {
         return result
       }
@@ -1398,17 +1399,22 @@ const handler =
       if (typeof thrown === 'number') {
         return new HttpResponse(null, { status: thrown })
       }
-      if (typeof thrown === 'function') {
-        return thrown()
-      }
       if (typeof thrown === 'string') {
         return json({ message: thrown }, { status: 400 })
       }
       if (thrown instanceof Response) {
         return thrown
       }
+
+      // if it's not one of those, then we don't know what to do with it
       console.error('Unexpected mock error', thrown)
-      return json({ message: 'Unknown Server Error' }, { status: 500 })
+      if (typeof thrown === 'function') {
+        console.error(
+          "It looks like you've accidentally thrown an error constructor function from a mock handler without calling it!"
+        )
+      }
+      // rethrow so everything breaks because this isn't supposed to happen
+      throw thrown
     }
   }
 
diff --git a/package-lock.json b/package-lock.json
index e75f3ec38f..6cb4fd8bc4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -56,7 +56,7 @@
         "@ianvs/prettier-plugin-sort-imports": "^4.3.0",
         "@ladle/react": "^4.1.0",
         "@mswjs/http-middleware": "^0.10.1",
-        "@oxide/openapi-gen-ts": "~0.2.2",
+        "@oxide/openapi-gen-ts": "~0.3.0",
         "@playwright/test": "^1.45.0",
         "@testing-library/dom": "^10.2.0",
         "@testing-library/jest-dom": "^6.4.6",
@@ -1979,10 +1979,11 @@
       }
     },
     "node_modules/@oxide/openapi-gen-ts": {
-      "version": "0.2.2",
-      "resolved": "https://registry.npmjs.org/@oxide/openapi-gen-ts/-/openapi-gen-ts-0.2.2.tgz",
-      "integrity": "sha512-PHJS2Gk98DfeMN0kMLGlL8Hy3SNkF4RGnPxMs/q8FJsmAFHtJu7hqoPpFIhfpjFYdFOP7gEKbWilstheBYdTUA==",
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/@oxide/openapi-gen-ts/-/openapi-gen-ts-0.3.0.tgz",
+      "integrity": "sha512-BiblEUJd+E3HgCmL3xZRtWXQ8AgaFVJ9KDm63nNt8pCg+HFpsTiEIJrlN1vaHx37gPkWk/Oi7tXGJOmPrpHfZg==",
       "dev": true,
+      "license": "MPL-2.0",
       "dependencies": {
         "minimist": "^1.2.8",
         "prettier": "2.7.1",
@@ -20081,9 +20082,9 @@
       }
     },
     "@oxide/openapi-gen-ts": {
-      "version": "0.2.2",
-      "resolved": "https://registry.npmjs.org/@oxide/openapi-gen-ts/-/openapi-gen-ts-0.2.2.tgz",
-      "integrity": "sha512-PHJS2Gk98DfeMN0kMLGlL8Hy3SNkF4RGnPxMs/q8FJsmAFHtJu7hqoPpFIhfpjFYdFOP7gEKbWilstheBYdTUA==",
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/@oxide/openapi-gen-ts/-/openapi-gen-ts-0.3.0.tgz",
+      "integrity": "sha512-BiblEUJd+E3HgCmL3xZRtWXQ8AgaFVJ9KDm63nNt8pCg+HFpsTiEIJrlN1vaHx37gPkWk/Oi7tXGJOmPrpHfZg==",
       "dev": true,
       "requires": {
         "minimist": "^1.2.8",
diff --git a/package.json b/package.json
index 9df3666a0c..15e662eecb 100644
--- a/package.json
+++ b/package.json
@@ -79,7 +79,7 @@
     "@ianvs/prettier-plugin-sort-imports": "^4.3.0",
     "@ladle/react": "^4.1.0",
     "@mswjs/http-middleware": "^0.10.1",
-    "@oxide/openapi-gen-ts": "~0.2.2",
+    "@oxide/openapi-gen-ts": "~0.3.0",
     "@playwright/test": "^1.45.0",
     "@testing-library/dom": "^10.2.0",
     "@testing-library/jest-dom": "^6.4.6",