Merge #20006: Fix misleading error message: Clean stack rule

af57766182 Fix misleading error message: Clean stack rule (sanket1729)

Pull request description:

  Error messages in clean stack is misleading as it lets the user believe that there are extra
  elements on the stack which is incorrect if the stack is empty.

  Let me know if this requires additional test.

ACKs for top commit:
  instagibbs:
    re-ACK af57766182
  gzhao408:
    reACK af57766182
  theStack:
    re-ACK af57766182
  darosior:
    re ACK af57766182

Tree-SHA512: 88e77416e220b080246fec368f5552a891d102d072b7bee62ac560d5e31c4a8c2ee9cbe569740b253e9df177d21dc788d10d856b2a542ab47761bb81698e4082

src/script/script_error.cpp

@@ -76,7 +76,7 @@ std::string ScriptErrorString(const ScriptError serror)
         case SCRIPT_ERR_PUBKEYTYPE:
             return "Public key is neither compressed or uncompressed";
         case SCRIPT_ERR_CLEANSTACK:
-            return "Extra items left on stack after execution";
+            return "Stack size must be exactly one after execution";
         case SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH:
             return "Witness program has incorrect length";
         case SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY: