Extending section: prevent duplicate mixin

Fixes #6809

panel/src/components/Sections/ModelsSection.vue

@@ -48,15 +48,13 @@
 
 <script>
 import debounce from "@/helpers/debounce";
+import section from "@/mixins/section";
 
 export default {
+	mixins: [section],
 	inheritAttrs: false,
 	props: {
-		blueprint: String,
-		column: String,
-		parent: String,
-		name: String,
-		timestamp: Number
+		column: String
 	},
 	data() {
 		return {

panel/src/mixins/section.js

@@ -1,7 +1,6 @@
 export default {
 	props: {
 		blueprint: String,
-		lock: [Boolean, Object],
 		help: String,
 		name: String,
 		parent: String,

panel/src/panel/plugins.js

@@ -127,9 +127,27 @@ export const installComponentMixins = (options) => {
 		section
 	};
 
-	options.mixins = options.mixins.map((mixin) =>
-		typeof mixin === "string" ? mixins[mixin] : mixin
-	);
+	options.mixins = options.mixins
+		.map((mixin) => {
+			// mixin got referenced by name
+			if (typeof mixin === "string" && mixins[mixin] !== undefined) {
+				// component inherits from a parent component:
+				// make sure to only include the mixin if the parent component
+				// hasn't already included it (to avoid duplicate mixins)
+				if (options.extends) {
+					const inherited = new options.extends().$options.mixins ?? [];
+
+					if (inherited.includes(mixins[mixin]) === true) {
+						return;
+					}
+				}
+
+				return mixins[mixin];
+			}
+
+			return mixin;
+		})
+		.filter((mixin) => mixin !== undefined);
 
 	return options;
 };