Handle invalid RPC escape sequences

apps/indexer/src/rpc.ts

@@ -12,6 +12,7 @@ function escapeControlCharactersInStrings(payload: string): string {
   let result = "";
   let inString = false;
   let escaping = false;
+  let unicodeDigitsRemaining = 0;
 
   for (let index = 0; index < payload.length; index += 1) {
     const char = payload[index];
@@ -25,7 +26,41 @@ function escapeControlCharactersInStrings(payload: string): string {
     }
 
     if (escaping) {
-      result += char;
+      if (unicodeDigitsRemaining > 0) {
+        if (/^[0-9a-fA-F]$/.test(char)) {
+          result += char;
+          unicodeDigitsRemaining -= 1;
+          if (unicodeDigitsRemaining === 0) {
+            escaping = false;
+          }
+          continue;
+        }
+
+        result += "\\u";
+        result += "0".repeat(unicodeDigitsRemaining);
+        unicodeDigitsRemaining = 0;
+        escaping = false;
+      }
+
+      if (char === "\"" || char === "\\" || char === "/" || char === "b" || char === "f" || char === "n" || char === "r" || char === "t") {
+        result += char;
+        escaping = false;
+        continue;
+      }
+
+      if (char === "u") {
+        result += char;
+        unicodeDigitsRemaining = 4;
+        continue;
+      }
+
+      result += "\\\\";
+      const code = char.charCodeAt(0);
+      if (code <= 0x1f) {
+        result += `u${code.toString(16).padStart(4, "0")}`;
+      } else {
+        result += char;
+      }
       escaping = false;
       continue;
     }