fix double load of positions now that check:config at startup is active (#3565)

after adding check:config to the MM startup process, #3450, we
accidentally discover module positions more than once, and write the
file each time..

add a check to see if we have done this work already

CHANGELOG.md

@@ -36,6 +36,7 @@ _This release is scheduled to be released on 2024-10-01._
 - [core] Detail optimizations in `config_check.js`
 - [core] Updated minimal needed node version in `package.json` (currently v20.9.0) (#3559) and except for v21 (no security updates) (#3561)
 - [linter] Switch to ESLint v9 and flat config and replace `eslint-plugin-unicorn` by `@eslint/js`
+- [core] fix discovering module positions twice after #3450
 
 ### Fixed
 

js/utils.js

@@ -49,6 +49,8 @@ module.exports = {
 	},
 
 	getModulePositions () {
+		// if not already discovered
+		if (modulePositions.length === 0) {
 			// get the lines of the index.html
 			const lines = fs.readFileSync(indexFileName).toString().split(os.EOL);
 			// loop thru the lines
@@ -64,6 +66,7 @@ module.exports = {
 				}
 			});
 			fs.writeFileSync(discoveredPositionsJSFilename, `const modulePositions=${JSON.stringify(modulePositions)}`);
+		}
 		// return the list to the caller
 		return modulePositions;
 	}