apply fix for #597 to neth

neth/main.cpp

@@ -379,13 +379,14 @@ int main(int argc, char** argv)
 				mining = ~(unsigned)0;
 			else if (isFalse(m))
 				mining = 0;
-			else if (int i = stoi(m))
-				mining = i;
 			else
-			{
-				cerr << "Unknown -m/--mining option: " << m << endl;
-				return -1;
-			}
+				try {
+					mining = stoi(m);
+				}
+				catch (...) {
+					cerr << "Unknown -m/--mining option: " << m << endl;
+					return -1;
+				}
 		}
 		else if (arg == "-b" || arg == "--bootstrap")
 			bootstrap = true;