diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e6a74332ee..8b9eda83d2 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -149,9 +149,12 @@ jobs:
       - name: Install Dependencies
         run: npm ci
 
-      - name: Run Tests
+      - name: Build the Package
         run: npm run build-package
 
+      - name: Generate the Legacy Build
+        run: npm run build-legacy
+
   rendering:
     name: Rendering
     runs-on: ubuntu-latest
diff --git a/config/jsdoc/api/conf.json b/config/jsdoc/api/conf.json
index 8fb5978971..a4a531ea2f 100644
--- a/config/jsdoc/api/conf.json
+++ b/config/jsdoc/api/conf.json
@@ -14,12 +14,13 @@
     ]
   },
   "plugins": [
-    "config/jsdoc/api/plugins/markdown.cjs",
+    "config/jsdoc/plugins/markdown.cjs",
     "jsdoc-plugin-typescript",
-    "config/jsdoc/api/plugins/inline-options.cjs",
-    "config/jsdoc/api/plugins/events.cjs",
-    "config/jsdoc/api/plugins/observable.cjs",
-    "config/jsdoc/api/plugins/api.cjs"
+    "config/jsdoc/plugins/inline-options.cjs",
+    "config/jsdoc/plugins/events.cjs",
+    "config/jsdoc/plugins/observable.cjs",
+    "config/jsdoc/plugins/api.cjs",
+    "config/jsdoc/plugins/default-export.cjs"
   ],
   "typescript": {
     "moduleRoot": "src"
diff --git a/config/jsdoc/info/conf.json b/config/jsdoc/info/conf.json
index 2997676be2..4d0838bff1 100644
--- a/config/jsdoc/info/conf.json
+++ b/config/jsdoc/info/conf.json
@@ -11,8 +11,9 @@
     },
     "plugins": [
         "jsdoc-plugin-typescript",
-        "config/jsdoc/info/define-plugin.cjs",
-        "config/jsdoc/info/virtual-plugin.cjs"
+        "config/jsdoc/plugins/define-plugin.cjs",
+        "config/jsdoc/plugins/virtual-plugin.cjs",
+        "config/jsdoc/plugins/default-export.cjs"
     ],
     "typescript": {
       "moduleRoot": "src"
diff --git a/config/jsdoc/info/publish.js b/config/jsdoc/info/publish.js
index 99b1b6b8d0..cdac68ea22 100644
--- a/config/jsdoc/info/publish.js
+++ b/config/jsdoc/info/publish.js
@@ -137,6 +137,9 @@ exports.publish = function (data, opts) {
             return true;
           });
         }
+        if (doc.isDefaultExport) {
+          symbol.isDefaultExport = true;
+        }
 
         const target = isExterns ? externs : symbols;
         const existingSymbol = symbolsByName[symbol.name];
diff --git a/config/jsdoc/api/plugins/api.cjs b/config/jsdoc/plugins/api.cjs
similarity index 83%
rename from config/jsdoc/api/plugins/api.cjs
rename to config/jsdoc/plugins/api.cjs
index 5a91e76a27..cd65cafecf 100644
--- a/config/jsdoc/api/plugins/api.cjs
+++ b/config/jsdoc/plugins/api.cjs
@@ -104,26 +104,6 @@ function includeTypes(doclet) {
   }
 }
 
-const defaultExports = {};
-const path = require('path');
-const moduleRoot = path.join(process.cwd(), 'src');
-
-// Tag default exported Identifiers because their name should be the same as the module name.
-exports.astNodeVisitor = {
-  visitNode: function (node, e, parser, currentSourceName) {
-    if (node.parent && node.parent.type === 'ExportDefaultDeclaration') {
-      const modulePath = path
-        .relative(moduleRoot, currentSourceName)
-        .replace(/\.js$/, '');
-      const exportName =
-        'module:' +
-        modulePath.replace(/\\/g, '/') +
-        (node.name ? '~' + node.name : '');
-      defaultExports[exportName] = true;
-    }
-  },
-};
-
 function sortOtherMembers(doclet) {
   if (doclet.fires) {
     doclet.fires.sort(function (a, b) {
@@ -198,18 +178,4 @@ exports.handlers = {
       }
     }
   },
-
-  processingComplete(e) {
-    const byLongname = e.doclets.index.longname;
-    for (const name in defaultExports) {
-      if (!(name in byLongname)) {
-        throw new Error(
-          `missing ${name} in doclet index, did you forget a @module tag?`
-        );
-      }
-      byLongname[name].forEach(function (doclet) {
-        doclet.isDefaultExport = true;
-      });
-    }
-  },
 };
diff --git a/config/jsdoc/plugins/default-export.cjs b/config/jsdoc/plugins/default-export.cjs
new file mode 100644
index 0000000000..ccab779aef
--- /dev/null
+++ b/config/jsdoc/plugins/default-export.cjs
@@ -0,0 +1,35 @@
+const defaultExports = {};
+const path = require('path');
+const moduleRoot = path.join(process.cwd(), 'src');
+
+// Tag default exported Identifiers because their name should be the same as the module name.
+exports.astNodeVisitor = {
+  visitNode: function (node, e, parser, currentSourceName) {
+    if (node.parent && node.parent.type === 'ExportDefaultDeclaration') {
+      const modulePath = path
+        .relative(moduleRoot, currentSourceName)
+        .replace(/\.js$/, '');
+      const exportName =
+        'module:' +
+        modulePath.replace(/\\/g, '/') +
+        (node.name ? '~' + node.name : '');
+      defaultExports[exportName] = true;
+    }
+  },
+};
+
+exports.handlers = {
+  processingComplete(e) {
+    const byLongname = e.doclets.index.longname;
+    for (const name in defaultExports) {
+      if (!(name in byLongname)) {
+        throw new Error(
+          `missing ${name} in doclet index, did you forget a @module tag?`
+        );
+      }
+      byLongname[name].forEach(function (doclet) {
+        doclet.isDefaultExport = true;
+      });
+    }
+  },
+};
diff --git a/config/jsdoc/info/define-plugin.cjs b/config/jsdoc/plugins/define-plugin.cjs
similarity index 100%
rename from config/jsdoc/info/define-plugin.cjs
rename to config/jsdoc/plugins/define-plugin.cjs
diff --git a/config/jsdoc/api/plugins/events.cjs b/config/jsdoc/plugins/events.cjs
similarity index 100%
rename from config/jsdoc/api/plugins/events.cjs
rename to config/jsdoc/plugins/events.cjs
diff --git a/config/jsdoc/api/plugins/inline-options.cjs b/config/jsdoc/plugins/inline-options.cjs
similarity index 100%
rename from config/jsdoc/api/plugins/inline-options.cjs
rename to config/jsdoc/plugins/inline-options.cjs
diff --git a/config/jsdoc/api/plugins/markdown.cjs b/config/jsdoc/plugins/markdown.cjs
similarity index 100%
rename from config/jsdoc/api/plugins/markdown.cjs
rename to config/jsdoc/plugins/markdown.cjs
diff --git a/config/jsdoc/api/plugins/observable.cjs b/config/jsdoc/plugins/observable.cjs
similarity index 100%
rename from config/jsdoc/api/plugins/observable.cjs
rename to config/jsdoc/plugins/observable.cjs
diff --git a/config/jsdoc/info/virtual-plugin.cjs b/config/jsdoc/plugins/virtual-plugin.cjs
similarity index 100%
rename from config/jsdoc/info/virtual-plugin.cjs
rename to config/jsdoc/plugins/virtual-plugin.cjs
diff --git a/package.json b/package.json
index 8bbbcb1a80..313b2e3371 100644
--- a/package.json
+++ b/package.json
@@ -21,8 +21,8 @@
     "serve-examples": "webpack serve --config examples/webpack/config.js --mode development",
     "build-examples": "webpack --config examples/webpack/config.js --mode production",
     "build-package": "npm run transpile && npm run copy-css && node tasks/prepare-package.js",
-    "build-index": "npm run build-package && node tasks/generate-index.js",
-    "build-legacy": "shx rm -rf build && npm run build-index && webpack --config config/webpack-config-legacy-build.js && cleancss --source-map src/ol/ol.css -o build/legacy/ol.css",
+    "build-index": "shx rm -f build/index.js && npm run build-package && node tasks/generate-index.js",
+    "build-legacy": "shx rm -rf build/legacy && npm run build-index && webpack --config config/webpack-config-legacy-build.js && cleancss --source-map src/ol/ol.css -o build/legacy/ol.css",
     "build-site": "npm run build-examples && npm run apidoc && mkdir -p build/site && cp site/index.html build/site && mv build/apidoc build/site/apidoc && mv build/examples build/site/examples",
     "copy-css": "shx cp src/ol/ol.css build/ol/ol.css",
     "transpile": "shx rm -rf build/ol && shx mkdir -p build/ol && shx cp -rf src/ol build/ol/src && node tasks/serialize-workers.cjs && tsc --project config/tsconfig-build.json",
diff --git a/tasks/generate-index.js b/tasks/generate-index.js
index c3e12f5acd..73d7fb3730 100644
--- a/tasks/generate-index.js
+++ b/tasks/generate-index.js
@@ -22,15 +22,20 @@ async function getSymbols() {
  */
 function getImport(symbol, member) {
   const defaultExport = symbol.name.split('~');
-  const namedExport = symbol.name.split('.');
-  if (defaultExport.length > 1 && defaultExport[0].indexOf('.') === -1) {
-    const from = defaultExport[0].replace(/^module\:/, './') + '.js';
+  if (symbol.isDefaultExport) {
+    const from = defaultExport[0].replace(/^module\:/, './');
     const importName = from.replace(/[.\/]+/g, '$');
-    return `import ${importName} from '${from}';`;
-  } else if (namedExport.length > 1 && member) {
-    const from = namedExport[0].replace(/^module\:/, './') + '.js';
+    return `import ${importName} from '${from}.js';`;
+  }
+  const namedExport = symbol.name.split('.');
+  if (
+    member &&
+    namedExport.length > 1 &&
+    (defaultExport.length <= 1 || defaultExport[0].indexOf('.') !== -1)
+  ) {
+    const from = namedExport[0].replace(/^module\:/, './');
     const importName = from.replace(/[.\/]+/g, '_');
-    return `import {${member} as ${importName}$${member}} from '${from}';`;
+    return `import {${member} as ${importName}$${member}} from '${from}.js';`;
   }
 }
 
@@ -44,24 +49,24 @@ function getImport(symbol, member) {
 function formatSymbolExport(symbol, namespaces, imports) {
   const name = symbol.name;
   const parts = name.split('~');
-  const isNamed = parts[0].indexOf('.') !== -1;
   const nsParts = parts[0].replace(/^module\:/, '').split(/[\/\.]/);
   const last = nsParts.length - 1;
-  const importName = isNamed
-    ? '_' + nsParts.slice(0, last).join('_') + '$' + nsParts[last]
-    : '$' + nsParts.join('$');
-  let line = nsParts[0];
-  for (let i = 1, ii = nsParts.length; i < ii; ++i) {
-    line += `.${nsParts[i]}`;
-    namespaces[line] =
-      (line in namespaces ? namespaces[line] : true) && i < ii - 1;
-  }
-  line += ` = ${importName} || {};`;
-  const imp = getImport(symbol, nsParts.pop());
+  const imp = getImport(symbol, nsParts[last]);
   if (imp) {
+    const isNamed = parts[0].indexOf('.') !== -1;
+    const importName = isNamed
+      ? '_' + nsParts.slice(0, last).join('_') + '$' + nsParts[last]
+      : '$' + nsParts.join('$');
+    let line = nsParts[0];
+    for (let i = 1, ii = nsParts.length; i < ii; ++i) {
+      line += `.${nsParts[i]}`;
+      namespaces[line] =
+        (line in namespaces ? namespaces[line] : true) && i < ii - 1;
+    }
+    line += ` = ${importName};`;
     imports[imp] = true;
+    return line;
   }
-  return line;
 }
 
 /**
@@ -71,7 +76,7 @@ function formatSymbolExport(symbol, namespaces, imports) {
  */
 function generateExports(symbols) {
   const namespaces = {};
-  const imports = [];
+  const imports = {};
   const blocks = [];
   symbols.forEach(function (symbol) {
     const name = symbol.name;
@@ -80,7 +85,10 @@ function generateExports(symbols) {
       if (imp) {
         imports[imp] = true;
       }
-      blocks.push(formatSymbolExport(symbol, namespaces, imports));
+      const line = formatSymbolExport(symbol, namespaces, imports);
+      if (line) {
+        blocks.push(line);
+      }
     }
   });
   const nsdefs = [];