Display warnings on components (#9108)

Closes #8678

[Peek 2024-02-20 12-45.webm](https://github.com/enso-org/enso/assets/1428930/6bb6c4ad-5507-4b11-b2c9-b295bf10c745)

app/gui2/src/components/GraphEditor/GraphNode.vue

@@ -1,7 +1,7 @@
 <script setup lang="ts">
 import { nodeEditBindings } from '@/bindings'
 import CircularMenu from '@/components/CircularMenu.vue'
-import GraphNodeError from '@/components/GraphEditor/GraphNodeError.vue'
+import GraphNodeError from '@/components/GraphEditor/GraphNodeMessage.vue'
 import GraphVisualization from '@/components/GraphEditor/GraphVisualization.vue'
 import NodeWidgetTree from '@/components/GraphEditor/NodeWidgetTree.vue'
 import SvgIcon from '@/components/SvgIcon.vue'
@@ -107,6 +107,15 @@ const error = computed(() => {
   }
 })
 
+const warning = computed(() => {
+  const externalId = graph.db.idToExternal(nodeId.value)
+  if (!externalId) return
+  const info = projectStore.computedValueRegistry.db.get(externalId)
+  const warning = info?.payload.type === 'Value' ? info.payload.warnings?.value : undefined
+  if (!warning) return
+  return '⚠ Warning: ' + warning!
+})
+
 const isSelected = computed(() => nodeSelection?.isSelected(nodeId.value) ?? false)
 watch(isSelected, (selected) => {
   if (!selected) {
@@ -331,6 +340,8 @@ watchEffect(() => {
   }
 })
 
+const nodeHovered = ref(false)
+
 function portGroupStyle(port: PortData) {
   const [start, end] = port.clipRange
   return {
@@ -368,6 +379,8 @@ function openFullMenu() {
       ['executionState-' + executionState]: true,
     }"
     :data-node-id="nodeId"
+    @pointerenter="nodeHovered = true"
+    @pointerleave="nodeHovered = false"
   >
     <div class="selection" v-on="dragPointer.events"></div>
     <div class="binding" @pointerdown.stop>
@@ -409,7 +422,14 @@ function openFullMenu() {
         <NodeWidgetTree :ast="displayedExpression" :nodeId="nodeId" />
       </div>
     </div>
-    <GraphNodeError v-if="error" class="error" :error="error" />
+    <GraphNodeError v-if="error" class="message" :message="error" type="error" />
+    <GraphNodeError
+      v-if="warning && (nodeHovered || isSelected)"
+      class="message warning"
+      :class="menuVisible === MenuState.Off ? '' : 'messageWithMenu'"
+      :message="warning"
+      type="warning"
+    />
     <svg class="bgPaths" :style="bgStyleVariables">
       <rect class="bgFill" />
       <template v-for="port of outputPorts" :key="port.portId">
@@ -631,9 +651,17 @@ function openFullMenu() {
   z-index: 1;
 }
 
-.error {
+.message {
   position: absolute;
   top: 100%;
   margin-top: 4px;
 }
+
+.messageWithMenu {
+  left: 40px;
+}
+
+.warning {
+  top: 35px;
+}
 </style>

app/gui2/src/components/GraphEditor/GraphNodeMessage.vue

@@ -0,0 +1,44 @@
+<script setup lang="ts">
+/// types of messages
+export type GraphNodeMessageType = 'error' | 'warning'
+
+const props = defineProps<{ message: string; type: GraphNodeMessageType }>()
+
+function styleClassForType(type: GraphNodeMessageType) {
+  switch (type) {
+    case 'error':
+      return 'GraphNodeError'
+    case 'warning':
+      return 'GraphNodeWarning'
+    default:
+      return ''
+  }
+}
+</script>
+
+<template>
+  <div class="GraphNodeMessage" :class="styleClassForType(props.type)" v-text="props.message"></div>
+</template>
+
+<style scoped>
+.GraphNodeMessage {
+  display: flex;
+  height: 24px;
+  padding: 1px 8px;
+  align-items: flex-start;
+  gap: 10px;
+  font-weight: 800;
+  white-space: nowrap;
+  border-radius: var(--radius-full);
+  color: var(--color-text-inversed);
+  line-height: 20px;
+}
+
+.GraphNodeWarning {
+  background-color: #faa212;
+}
+
+.GraphNodeError {
+  background-color: #e85252;
+}
+</style>