Add an error check for a missing -node parameter in the Ssurgeon SplitWord operation

Author: AngledLuffa

src/edu/stanford/nlp/semgraph/semgrex/ssurgeon/Ssurgeon.java

@@ -682,6 +682,9 @@ public static SsurgeonEdit parseEditLine(String editLine, Map<String, String> at
         if (argsBox.regex.size() > 0 && argsBox.exact.size() > 0) {
           throw new SsurgeonParseException("Found both regex and exact in the splits for splitWord");
         }
+        if (argsBox.nodes.size() == 0) {
+          throw new SsurgeonParseException("splitWord not given any -node parameter for the node to split");
+        }
         if (argsBox.regex.size() > 0) {
           return new SplitWord(argsBox.nodes.get(0), argsBox.regex, argsBox.headIndex, reln, argsBox.name, false);
         } else {