external_signer: remove ExternalSignerException

It's not clear why this need it's own exception class, as opposed to just
throwing std::runtime_error().

src/external_signer.cpp

@@ -9,6 +9,7 @@
 #include <util/system.h>
 #include <external_signer.h>
 
+#include <stdexcept>
 #include <string>
 #include <vector>
 
@@ -26,21 +27,21 @@ bool ExternalSigner::Enumerate(const std::string& command, std::vector<ExternalS
     // Call <command> enumerate
     const UniValue result = RunCommandParseJSON(command + " enumerate");
     if (!result.isArray()) {
-        throw ExternalSignerException(strprintf("'%s' received invalid response, expected array of signers", command));
+        throw std::runtime_error(strprintf("'%s' received invalid response, expected array of signers", command));
     }
     for (UniValue signer : result.getValues()) {
         // Check for error
         const UniValue& error = find_value(signer, "error");
         if (!error.isNull()) {
             if (!error.isStr()) {
-                throw ExternalSignerException(strprintf("'%s' error", command));
+                throw std::runtime_error(strprintf("'%s' error", command));
             }
-            throw ExternalSignerException(strprintf("'%s' error: %s", command, error.getValStr()));
+            throw std::runtime_error(strprintf("'%s' error: %s", command, error.getValStr()));
         }
         // Check if fingerprint is present
         const UniValue& fingerprint = find_value(signer, "fingerprint");
         if (fingerprint.isNull()) {
-            throw ExternalSignerException(strprintf("'%s' received invalid response, missing signer fingerprint", command));
+            throw std::runtime_error(strprintf("'%s' received invalid response, missing signer fingerprint", command));
         }
         const std::string fingerprintStr = fingerprint.get_str();
         // Skip duplicate signer

src/external_signer.h

@@ -8,7 +8,6 @@
 #include <univalue.h>
 #include <util/system.h>
 
-#include <stdexcept>
 #include <string>
 #include <vector>
 
@@ -16,11 +15,6 @@
 
 struct PartiallySignedTransaction;
 
-class ExternalSignerException : public std::runtime_error {
-public:
-    using std::runtime_error::runtime_error;
-};
-
 //! Enables interaction with an external signing device or service, such as
 //! a hardware wallet. See doc/external-signer.md
 class ExternalSigner

src/rpc/external_signer.cpp

@@ -49,7 +49,7 @@ static RPCHelpMan enumeratesigners()
                     signer_res.pushKV("name", signer.m_name);
                     signers_res.push_back(signer_res);
                 }
-            } catch (const ExternalSignerException& e) {
+            } catch (const std::exception& e) {
                 throw JSONRPCError(RPC_MISC_ERROR, e.what());
             }
             UniValue result(UniValue::VOBJ);