generation of custom error unpacking builds (not tested yet)

accounts/abi/bind/bind.go

@@ -70,6 +70,10 @@ func isKeyWord(arg string) bool {
 	return true
 }
 
+func add(val1, val2 int) int {
+	return val1 + val1
+}
+
 // Bind generates a Go wrapper around a contract ABI. This wrapper isn't meant
 // to be used as is in client code, but rather as an intermediate struct which
 // enforces compile time type safety and naming convention as opposed to having to
@@ -146,6 +150,7 @@ func BindV2(types []string, abis []string, bytecodes []string, fsigs []map[strin
 		"bindtopictype": bindTopicType,
 		"capitalise":    capitalise,
 		"decapitalise":  decapitalise,
+		"add":           add,
 	}
 	tmpl := template.Must(template.New("").Funcs(funcs).Parse(tmplSourceV2))
 	if err := tmpl.Execute(buffer, data); err != nil {

accounts/abi/bind/source2.go.tpl

@@ -151,6 +151,24 @@ var (
 		}
 	{{end}}
 
+    {{ if .Errors }}
+    func (_{{$contract.Type}} *{{$contract.Type}}) UnpackError(raw []byte) any {
+        {{$i := 0}}
+        {{range $k, $v := .Errors}}
+            {{ if eq $i 0 }}
+                if val, err := _{{$contract.Type}}.Unpack{{.Normalized.Name}}Error(raw); err != nil {
+                    return val
+            {{ else }}
+                } else if val, err := _{{$contract.Type}}.Unpack{{.Normalized.Name}}Error(raw); err != nil {
+                    return val
+            {{ end -}}
+            {{$i = add $i 1}}
+        {{end -}}
+        }
+        return nil
+    }
+    {{ end -}}
+
     {{range .Errors}}
 		// {{$contract.Type}}{{.Normalized.Name}} represents a {{.Normalized.Name}} error raised by the {{$contract.Type}} contract.
 		type {{$contract.Type}}{{.Normalized.Name}} struct { {{range .Normalized.Inputs}}