eth/tracers: avoid returning nil in unigram tracer

Author: s1na

eth/tracers/internal/tracers/assets.go

@@ -36,8 +36,6 @@
     // result is invoked when all the opcodes have been iterated over and returns
     // the final result of the tracing.
     result: function(ctx) {
-        if(this.nops > 0){
-            return this.hist;
-        }
+        return this.hist;
     },
 }