fix some no-jquery/no-extend autofixes (wikimedia-gadgets#2088)

* revert some no-jquery/no-extend autofixes

Upstream, they caught a bug in the autofix algorithm. Basically, you should only change $.extend() to Object.assign() if you're sure the first argument isn't null or undefined. Else it will throw.

This patch changes a couple back to $.extend, out of an abundance of caution.

wikimedia/eslint-plugin-no-jquery@35d4489

Partial revert of wikimedia-gadgets#2079

* instead of reverting, add `|| {}`

modules/twinkleblock.js

@@ -1899,7 +1899,7 @@ Twinkle.block.callback.issue_template = function twinkleblockCallbackIssueTempla
 	// "talk page" of an IP range (which does not exist)
 	const userTalkPage = 'User_talk:' + mw.config.get('wgRelevantUserName');
 
-	const params = Object.assign(formData, {
+	const params = Object.assign(formData || {}, {
 		messageData: Twinkle.block.blockPresetsInfo[formData.template],
 		reason: Twinkle.block.field_template_options.block_reason,
 		disabletalk: Twinkle.block.field_template_options.notalk,

morebits.js

@@ -758,7 +758,7 @@ Morebits.quickForm.element.prototype.compute = function QuickFormElementCompute(
 			node = document.createElement('div');
 
 			data.inputs.forEach((subdata) => {
-				const cell = new Morebits.quickForm.element(Object.assign(subdata, { type: '_dyninput_cell' }));
+				const cell = new Morebits.quickForm.element(Object.assign(subdata || {}, { type: '_dyninput_cell' }));
 				node.appendChild(cell.render());
 			});
 			if (data.remove) {

twinkle.js

@@ -337,7 +337,7 @@ $.ajax({
 			const options = JSON.parse(optionsText);
 			if (options) {
 				if (options.twinkle || options.friendly) { // Old preferences format
-					Twinkle.prefs = Object.assign(options.twinkle, options.friendly);
+					Twinkle.prefs = Object.assign(options.twinkle || {}, options.friendly);
 				} else {
 					Twinkle.prefs = options;
 				}