fix: filter out empty strings in server arguments to prevent parseArgs error

When running 'npx .' without any arguments, empty strings were being passed
as positional arguments to the server, causing Node.js parseArgs to fail with
'Unexpected argument' error. This fix filters out empty strings from the
arguments array before passing them to spawnPromise.

Also added a test to verify the web client can start without any arguments,
preventing regression of this issue.

Author: felixweinberger

cli/scripts/cli-tests.js

@@ -299,8 +299,111 @@ async function runErrorTest(testName, ...args) {
   }
 }
 
+// Function to run a web client startup test
+async function runWebClientTest(testName, ...args) {
+  const outputFile = path.join(
+    OUTPUT_DIR,
+    `${testName.replace(/\//g, "_")}.log`,
+  );
+
+  console.log(`\n${colors.YELLOW}Testing: ${testName}${colors.NC}`);
+  TOTAL_TESTS++;
+
+  // Run the command and capture output
+  console.log(
+    `${colors.BLUE}Command: node ${BUILD_DIR}/cli.js ${args.join(" ")}${colors.NC}`,
+  );
+
+  try {
+    // Create a write stream for the output file
+    const outputStream = fs.createWriteStream(outputFile);
+
+    // Spawn the process
+    return new Promise((resolve) => {
+      const child = spawn("node", [path.join(BUILD_DIR, "cli.js"), ...args], {
+        stdio: ["ignore", "pipe", "pipe"],
+        env: {
+          ...process.env,
+          MCP_AUTO_OPEN_ENABLED: "false", // Prevent browser from opening
+          SERVER_PORT: "9999", // Use a different port for testing
+          CLIENT_PORT: "9998", // Use a different port for testing
+        },
+      });
+
+      let output = "";
+      let serverStarted = false;
+
+      child.stdout.on("data", (data) => {
+        output += data.toString();
+        outputStream.write(data);
+        
+        // Check if server started successfully
+        if (output.includes("MCP Inspector is up and running")) {
+          serverStarted = true;
+          // Kill the process after successful startup
+          child.kill();
+        }
+      });
+
+      child.stderr.on("data", (data) => {
+        output += data.toString();
+        outputStream.write(data);
+      });
+
+      const timeout = setTimeout(() => {
+        console.log(`${colors.YELLOW}Test timed out: ${testName}${colors.NC}`);
+        child.kill();
+      }, 5000); // 5 second timeout for web client startup
+
+      child.on("close", (code) => {
+        clearTimeout(timeout);
+        outputStream.end();
+
+        if (serverStarted) {
+          console.log(`${colors.GREEN}✓ Test passed: ${testName}${colors.NC}`);
+          console.log(`${colors.BLUE}Server started successfully${colors.NC}`);
+          PASSED_TESTS++;
+          resolve(true);
+        } else {
+          console.log(`${colors.RED}✗ Test failed: ${testName}${colors.NC}`);
+          console.log(`${colors.RED}Error output:${colors.NC}`);
+          console.log(
+            output
+              .split("\n")
+              .map((line) => `  ${line}`)
+              .join("\n"),
+          );
+          FAILED_TESTS++;
+          
+          // Stop after any error is encountered
+          console.log(
+            `${colors.YELLOW}Stopping tests due to error. Please validate and fix before continuing.${colors.NC}`,
+          );
+          process.exit(1);
+        }
+      });
+    });
+  } catch (error) {
+    console.error(
+      `${colors.RED}Error running test: ${error.message}${colors.NC}`,
+    );
+    FAILED_TESTS++;
+    process.exit(1);
+  }
+}
+
 // Run all tests
 async function runTests() {
+  console.log(
+    `\n${colors.YELLOW}=== Running Basic Tests ===${colors.NC}`,
+  );
+
+  // Test 0: Basic web client mode without any arguments (regression test for npx .)
+  await runWebClientTest(
+    "web_client_no_args"
+    // No arguments - should start web client without error
+  );
+
   console.log(
     `\n${colors.YELLOW}=== Running Basic CLI Mode Tests ===${colors.NC}`,
   );

client/bin/start.js

@@ -95,7 +95,7 @@ async function startProdServer(serverOptions) {
       mcpServerArgs && mcpServerArgs.length > 0
         ? `--args=${mcpServerArgs.join(" ")}`
         : "",
-    ],
+    ].filter(arg => arg !== ""),
     {
       env: {
         ...process.env,