fix: reduce compliance fix complexity (#4630)

Signed-off-by: jasuwienas <[email protected]>

Author: jasuwienas

packages/server/src/compliance.ts

@@ -34,26 +34,47 @@ export const jsonRpcComplianceLayer = async (
     status: number | undefined;
   } & ParameterizedContext,
 ) => {
-  if (!ctx.body) {
+  const fallback = FALLBACK_RESPONSE_BODY;
+
+  const setBadRequest = () => {
     ctx.status = 400;
-    ctx.body = FALLBACK_RESPONSE_BODY;
+    ctx.body = fallback;
+  };
+
+  const ensureBaseFields = () => {
+    ctx.body.jsonrpc ||= fallback.jsonrpc;
+    ctx.body.id ||= fallback.id;
+  };
+
+  const normalizeErrorStatus = () => {
+    const isBadReq = ctx.status === 400;
+    const missingError = !ctx.body.error || !ctx.body.error.code;
+
+    if (isBadReq && missingError) ctx.body.error = fallback.error;
+    if (isBadReq && VALID_JSON_RPC_HTTP_REQUESTS_STATUS_CODE) ctx.status = 200;
+  };
+
+  if (!ctx.body) {
+    setBadRequest();
     return;
   }
 
-  // Always return 200 for array requests.
   if (Array.isArray(ctx.body)) {
     ctx.status = 200;
     return;
   }
+
   if (typeof ctx.body !== 'object') {
-    ctx.status = 400;
-    ctx.body = FALLBACK_RESPONSE_BODY;
+    setBadRequest();
     return;
   }
 
-  if (!ctx.body.jsonrpc) ctx.body.jsonrpc = FALLBACK_RESPONSE_BODY.jsonrpc;
-  if (!ctx.body.id) ctx.body.id = FALLBACK_RESPONSE_BODY.id;
-  if (ctx.status === 200 && !ctx.body.result) ctx.body.result = '0x';
-  if (ctx.status === 400 && (!ctx.body.error || !ctx.body.error.code)) ctx.body.error = FALLBACK_RESPONSE_BODY.error;
-  if (ctx.status === 400 && VALID_JSON_RPC_HTTP_REQUESTS_STATUS_CODE) ctx.status = 200;
+  ensureBaseFields();
+
+  if (ctx.status === 200 && !ctx.body.result) {
+    ctx.body.result = '0x';
+  }
+
+  normalizeErrorStatus();
 };
+