Fix thelounge uninstall command

- Exit with code 1 when package was not installed
- Run a pre-step to check if package is installed before uninstalling. I have tried every possible way I could think of without that first `npm list` step based on output of `npm uninstall`, but different npm versions produce different outputs, so there is nothing reliable. This is a more robust way to do so anyway.
- Consolidate error handlers

src/command-line/uninstall.js

@@ -28,11 +28,54 @@ program
 
 		if (!fs.existsSync(packagesConfig)) {
 			log.warn(packageWasNotInstalled);
-			return;
+			process.exit(1);
 		}
 
-		const npm = child.spawn(
-			process.platform === "win32" ? "npm.cmd" : "npm",
+		const npm = process.platform === "win32" ? "npm.cmd" : "npm";
+		const errorHandler = (error) => {
+			log.error(
+				`Failed to uninstall ${colors.green(packageName)}. ` +
+				`${typeof x === "number" ? "Exit code" : "Error"}: ${error}`
+			);
+			process.exit(1);
+		};
+
+		// First, we check if the package is installed with `npm list`
+		const list = child.spawn(
+			npm,
+			[
+				"list",
+				"--depth",
+				"0",
+				"--prefix",
+				packagesParent,
+				packageName,
+			],
+			{
+				// This is the same as `"inherit"` except:
+				// - `process.stdout` is piped so we can test if the output mentions the
+				//   package was found
+				// - `process.stderr` is ignored to silence `npm ERR! extraneous` errors
+				stdio: [process.stdin, "pipe", "ignore"],
+			}
+		);
+
+		list.stdout.on("data", (data) => {
+			// If the package name does not appear in stdout, it means it was not
+			// installed. We cannot rely on exit code because `npm ERR! extraneous`
+			// causes a status of 1 even if package exists.
+			if (!data.toString().includes(packageName)) {
+				log.warn(packageWasNotInstalled);
+				process.exit(1);
+			}
+		});
+
+		list.on("error", errorHandler);
+
+		list.on("close", () => {
+			// If we get there, it means the package exists, so uninstall
+			const uninstall = child.spawn(
+				npm,
 				[
 					"uninstall",
 					"--no-progress",
@@ -41,32 +84,19 @@ program
 					packageName,
 				],
 				{
-				// This is the same as `"inherit"` except `process.stdout` is piped
-				stdio: [process.stdin, "pipe", process.stderr],
+					// This is the same as `"inherit"` except `process.stdout` is silenced
+					stdio: [process.stdin, "ignore", process.stderr],
 				}
 			);
 
-		let hasUninstalled = false;
+			uninstall.on("error", errorHandler);
 
-		npm.stdout.on("data", () => {
-			hasUninstalled = true;
-		});
-
-		npm.on("error", (e) => {
-			log.error(`${e}`);
-			process.exit(1);
-		});
-
-		npm.on("close", (code) => {
+			uninstall.on("close", (code) => {
 				if (code !== 0) {
-				log.error(`Failed to uninstall ${colors.green(packageName)}. Exit code: ${code}`);
-				return;
+					errorHandler(code);
 				}
 
-			if (hasUninstalled) {
 				log.info(`${colors.green(packageName)} has been successfully uninstalled.`);
-			} else {
-				log.warn(packageWasNotInstalled);
-			}
+			});
 		});
 	});