Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
Your rows dot where filter contains a dollar word that rush does not know. Here is how filters are built. A condition is a nested map. Some keys are operators, such as dollar eq for equals, dollar lt for less than, dollar contains, dollar starts with, dollar null, and a family of siblings. Others are logic words: dollar and, dollar or, and dollar not. Any other dollar word is neither, so it means nothing. Rush reads the whole condition before it looks at the first record. That means a typo is caught even if it hides in a branch that no record would ever reach, so you do not find out much later, on a day when the right data shows up. And the engine never guesses what the unknown word was supposed to be, since a wrong guess would silently return the wrong rows. The first slot names the word, and the second says where the legal words are listed. If your server takes the condition from a client, check the words first, and answer the client with the error. Fix the spelling, and the filter runs.
Text from the Rush engine's error catalogue.