gistfile1.diff

diff --git a/plugins/supported/standard_syntax.js b/plugins/supported/standard_syntax.js
--- a/plugins/supported/standard_syntax.js
+++ b/plugins/supported/standard_syntax.js
@@ -83,6 +83,9 @@
                 if (then.length > 1) {
                     newContext = then[1].split(":");
                 }
+            } else if (len === 0) {
+                throw new Error("StandardSyntax: Infinite loop detected: " +
+                    "zero-length match that didn't change state");
             } else {
                 nextState = fullState;
             }