fix: update error stack traces for Cypress (#239)

Fixes #232

Update the Cypress error message rather than the entire error object. This merges the useful message of DOM Testing Library with the useful context of the Cypress error. This allows Cypress to find the line number of the failure in spec files instead of deep inside DOM Testing Library.

src/index.js

@@ -109,7 +109,7 @@ function createCommand(queryName, implementationName) {
               onFail: () => {
                 // We want to override Cypress's normal non-existence message with @testing-library/dom's more helpful ones
                 if (error) {
-                  options.error = error
+                  options.error.message = error.message
                 }
               },
             })