Merge bd51be4493 into 9f98d803c0

- Add conditional check for module.default property in SystemLibraryPlugin
- Handle both ES6 modules (with default property) and SystemJS modules (without default property)
- Fixes issue where default imports returned undefined instead of module object
- Maintains backward compatibility with existing functionality
- Resolves #19950

lib/library/SystemLibraryPlugin.js

@@ -133,7 +133,20 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 											chunk.runtime
 										);
 										if (used) {
-											if (otherUnused || used !== exportInfo.name) {
+											if (used === "default" && exportInfo.name === "default") {
+												instructions.push(
+													Template.asString([
+														"if (typeof module.default !== 'undefined') {",
+														Template.indent([
+															`${external}.default = module.default;`
+														]),
+														"} else {",
+														Template.indent([`${external} = module;`]),
+														"}"
+													])
+												);
+												handledNames.push(exportInfo.name);
+											} else if (otherUnused || used !== exportInfo.name) {
 												instructions.push(
 													`${external}${propertyAccess([
 														used
@@ -172,9 +185,24 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 										} else {
 											instructions.push(
 												Template.asString([
-													"Object.keys(module).forEach(function(key) {",
-													Template.indent([`${external}[key] = module[key];`]),
-													"});"
+													"if (typeof module.default !== 'undefined') {",
+													Template.indent([
+														"Object.keys(module).forEach(function(key) {",
+														Template.indent([
+															`${external}[key] = module[key];`
+														]),
+														"});"
+													]),
+													"} else {",
+													Template.indent([
+														`${external} = module;`,
+														"Object.keys(module).forEach(function(key) {",
+														Template.indent([
+															`${external}[key] = module[key];`
+														]),
+														"});"
+													]),
+													"}"
 												])
 											);
 										}