diff --git a/apps/workflowengine/src/components/Checks/FileMimeType.vue b/apps/workflowengine/src/components/Checks/FileMimeType.vue
index 862c4a4201..e91636f513 100644
--- a/apps/workflowengine/src/components/Checks/FileMimeType.vue
+++ b/apps/workflowengine/src/components/Checks/FileMimeType.vue
@@ -33,12 +33,12 @@
 			@input="setValue">
 			<template slot="singleLabel" slot-scope="props">
 				<span v-if="props.option.icon" class="option__icon" :class="props.option.icon" />
-				<img v-else :src="props.option.iconUrl" />
+				<img v-else :src="props.option.iconUrl">
 				<span class="option__title option__title_single">{{ props.option.label }}</span>
 			</template>
 			<template slot="option" slot-scope="props">
 				<span v-if="props.option.icon" class="option__icon" :class="props.option.icon" />
-				<img v-else :src="props.option.iconUrl" />
+				<img v-else :src="props.option.iconUrl">
 				<span class="option__title">{{ props.option.label }}</span>
 			</template>
 		</Multiselect>
diff --git a/apps/workflowengine/src/components/Checks/RequestTime.vue b/apps/workflowengine/src/components/Checks/RequestTime.vue
index cd702ecae8..196f3e2afa 100644
--- a/apps/workflowengine/src/components/Checks/RequestTime.vue
+++ b/apps/workflowengine/src/components/Checks/RequestTime.vue
@@ -10,7 +10,9 @@
 			type="text"
 			placeholder="e.g. 18:00"
 			@input="update">
-		<p v-if="!valid" class="invalid-hint">{{ t('workflowengine', 'Please enter a valid time span')}}</p>
+		<p v-if="!valid" class="invalid-hint">
+			{{ t('workflowengine', 'Please enter a valid time span') }}
+		</p>
 	</div>
 </template>
 
@@ -56,7 +58,9 @@ export default {
 						timezone: data[0].split(' ', 2)[1]
 					}
 				}
-			} catch (e) {}
+			} catch (e) {
+				// ignore invalid values
+			}
 		},
 		validate() {
 			return this.newValue.startTime && this.newValue.startTime.match(/^(0[0-9]|1[0-9]|2[0-3]|[0-9]):[0-5][0-9]$/i) !== null
diff --git a/apps/workflowengine/src/components/Event.vue b/apps/workflowengine/src/components/Event.vue
index 1afdfa80be..97608fde06 100644
--- a/apps/workflowengine/src/components/Event.vue
+++ b/apps/workflowengine/src/components/Event.vue
@@ -15,7 +15,7 @@
 			<template slot="selection" slot-scope="{ values, search, isOpen }">
 				<div v-if="values.length && !isOpen" class="eventlist">
 					<img class="option__icon" :src="values[0].entity.icon">
-					<span class="text option__title option__title_single" v-for="(value, index) in values">{{ value.displayName }} <span v-if="index+1 < values.length">, </span></span>
+					<span v-for="(value, index) in values" :key="value.id" class="text option__title option__title_single">{{ value.displayName }} <span v-if="index+1 < values.length">, </span></span>
 				</div>
 			</template>
 			<template slot="option" slot-scope="props">
diff --git a/apps/workflowengine/src/helpers/validators.js b/apps/workflowengine/src/helpers/validators.js
index 4936b9200f..d64adfa138 100644
--- a/apps/workflowengine/src/helpers/validators.js
+++ b/apps/workflowengine/src/helpers/validators.js
@@ -27,24 +27,21 @@ const validateRegex = function(string) {
 	if (!string) {
 		return false
 	}
-	const result = regexRegex.exec(string)
-	return result !== null
+	return regexRegex.exec(string) !== null
 }
 
 const validateIPv4 = function(string) {
 	if (!string) {
 		return false
 	}
-	const result = regexIPv4.exec(string)
-	return result !== null
+	return regexIPv4.exec(string) !== null
 }
 
 const validateIPv6 = function(string) {
 	if (!string) {
 		return false
 	}
-	const result = regexIPv6.exec(string)
-	return result !== null
+	return regexIPv6.exec(string) !== null
 }
 
 const stringValidator = (check) => {
diff --git a/apps/workflowengine/src/store.js b/apps/workflowengine/src/store.js
index cbd9b29c81..a18540f803 100644
--- a/apps/workflowengine/src/store.js
+++ b/apps/workflowengine/src/store.js
@@ -71,7 +71,9 @@ const store = new Vuex.Store({
 			plugin = Object.assign(
 				{ color: 'var(--color-primary-element)' },
 				plugin, state.operations[plugin.id] || {})
-			Vue.set(state.operations, plugin.id, plugin)
+			if (typeof state.operations[plugin.id] !== 'undefined') {
+				Vue.set(state.operations, plugin.id, plugin)
+			}
 		}
 	},
 	actions: {