fix: small fixes

Author: arnaudbriche

json/decode_log.go

@@ -12,7 +12,7 @@ func DecodeLog(topics [][]byte, input []byte, event eth_abi.Event) (ast.Node, er
 
 	// mismatch btw num of indexed fields and num of topics
 	if len(indexed) != (len(topics) - 1) {
-		return ast.Node{}, fmt.Errorf("event has %d indexed inputs but log has %d topics", len(indexed), (len(topics) - 1))
+		return ast.Node{}, fmt.Errorf("event has %d indexed inputs but log has %d topics", len(indexed), len(topics))
 	}
 
 	// log has data but abi field does not have unindexed fields

json/decode_trace.go

@@ -8,6 +8,10 @@ import (
 )
 
 func DecodeTrace(input []byte, output []byte, method eth_abi.Method) (ast.Node, error) {
+	if len(input) < 4 {
+		return ast.Node{}, fmt.Errorf("trace input is smaller than 4 bytes")
+	}
+
 	if len(method.Outputs) == 0 && len(output) > 0 {
 		return ast.Node{}, fmt.Errorf("trace has output data but method has no outputs")
 	}