Updated the files.

my-app/node_modules/webpack-dev-server/client/overlay/state-machine.js

@@ -0,0 +1,100 @@
+import createMachine from "./fsm.js";
+
+/**
+ * @typedef {Object} ShowOverlayData
+ * @property {'warning' | 'error'} level
+ * @property {Array<string  | { moduleIdentifier?: string, moduleName?: string, loc?: string, message?: string }>} messages
+ * @property {'build' | 'runtime'} messageSource
+ */
+
+/**
+ * @typedef {Object} CreateOverlayMachineOptions
+ * @property {(data: ShowOverlayData) => void} showOverlay
+ * @property {() => void} hideOverlay
+ */
+
+/**
+ * @param {CreateOverlayMachineOptions} options
+ */
+var createOverlayMachine = function createOverlayMachine(options) {
+  var hideOverlay = options.hideOverlay,
+    showOverlay = options.showOverlay;
+  var overlayMachine = createMachine({
+    initial: "hidden",
+    context: {
+      level: "error",
+      messages: [],
+      messageSource: "build"
+    },
+    states: {
+      hidden: {
+        on: {
+          BUILD_ERROR: {
+            target: "displayBuildError",
+            actions: ["setMessages", "showOverlay"]
+          },
+          RUNTIME_ERROR: {
+            target: "displayRuntimeError",
+            actions: ["setMessages", "showOverlay"]
+          }
+        }
+      },
+      displayBuildError: {
+        on: {
+          DISMISS: {
+            target: "hidden",
+            actions: ["dismissMessages", "hideOverlay"]
+          },
+          BUILD_ERROR: {
+            target: "displayBuildError",
+            actions: ["appendMessages", "showOverlay"]
+          }
+        }
+      },
+      displayRuntimeError: {
+        on: {
+          DISMISS: {
+            target: "hidden",
+            actions: ["dismissMessages", "hideOverlay"]
+          },
+          RUNTIME_ERROR: {
+            target: "displayRuntimeError",
+            actions: ["appendMessages", "showOverlay"]
+          },
+          BUILD_ERROR: {
+            target: "displayBuildError",
+            actions: ["setMessages", "showOverlay"]
+          }
+        }
+      }
+    }
+  }, {
+    actions: {
+      dismissMessages: function dismissMessages() {
+        return {
+          messages: [],
+          level: "error",
+          messageSource: "build"
+        };
+      },
+      appendMessages: function appendMessages(context, event) {
+        return {
+          messages: context.messages.concat(event.messages),
+          level: event.level || context.level,
+          messageSource: event.type === "RUNTIME_ERROR" ? "runtime" : "build"
+        };
+      },
+      setMessages: function setMessages(context, event) {
+        return {
+          messages: event.messages,
+          level: event.level || context.level,
+          messageSource: event.type === "RUNTIME_ERROR" ? "runtime" : "build"
+        };
+      },
+      hideOverlay: hideOverlay,
+      showOverlay: showOverlay
+    }
+  });
+  return overlayMachine;
+};
+export default createOverlayMachine;