@@ -535,9 +535,7 @@ up.Params = class Params {
 
     // Fields and buttons that a preview disabled still count, e.g. for a second submission
     // while the first one is loading.
-    let disableAgain = up.form.enablePreviewDisabledTemp(form)
-
-    try {
+    return up.form.withPreviewFieldsEnabled(form, () => {
       // We let the browser serialize the form, instead of iterating over up.form.fields():
       //
       // - Only the browser can read the value of a form-associated custom element. The element
@@ -563,9 +561,7 @@ up.Params = class Params {
         if (!browserControls.has(field) && !field.closest('fieldset:disabled')) params.addField(field)
       }
       return params
-    } finally {
-      disableAgain()
-    }
+    })
   }
 
   static fromContainer(container, options) {
 
@@ -670,11 +670,17 @@ up.form = (function() {
     }
   }
 
-  // Re-enables the controls that a preview has disabled, e.g. to read their params.
-  // Returns a function that disables them again.
-  function enablePreviewDisabledTemp(form) {
+  // Runs the given function while the controls that a preview has disabled are enabled,
+  // e.g. to read their params. Disables them again afterwards.
+  function withPreviewFieldsEnabled(form, fn) {
     let controls = findFieldsAndButtons(form).filter((control) => control.upPreviewDisabled && readFieldDisabled(control))
-    return u.sequence(u.map(controls, (control) => writeFieldDisabled(control, false)))
+    let disableAgain = u.sequence(u.map(controls, (control) => writeFieldDisabled(control, false)))
+
+    try {
+      return fn()
+    } finally {
+      disableAgain()
+    }
   }
 
   function setContainerDisabled(container, disabled) {
@@ -2455,7 +2461,7 @@ up.form = (function() {
     focusedField,
     // disableWhile,
     disableTemp: disableContainerTemp,
-    enablePreviewDisabledTemp,
+    withPreviewFieldsEnabled,
     setDisabled: setContainerDisabled,
     getDisablePreviewFn,
     // handleDisableOption,