Fix parseLog signature when receiving read-only array for topics (#4029…

…, #4459).

src.ts/abi/interface.ts

@@ -1212,7 +1212,7 @@ export class Interface {
      *
      *  If the matching event cannot be found, returns null.
      */
-    parseLog(log: { topics: Array<string>, data: string}): null | LogDescription {
+    parseLog(log: { topics: ReadonlyArray<string>, data: string}): null | LogDescription {
         const fragment = this.getEvent(log.topics[0]);
 
         if (!fragment || fragment.anonymous) { return null; }