fix: safely handle logging and filesystem errors

Author: naji247

.gitignore

@@ -67,3 +67,6 @@ coverage
 
 # Changeset files (optional, some projects want to track these)
 # .changeset/
+.serena
+AGENTS.md
+

src/modules/logging.ts

@@ -2,9 +2,24 @@ import { writeFileSync, appendFileSync, existsSync } from "fs";
 import { homedir } from "os";
 import { join } from "path";
 
-const LOG_FILE = join(homedir(), "mcpcat.log");
+// Safely determine log file path, handling environments where homedir() may return null
+let LOG_FILE: string | null = null;
+try {
+  const home = homedir();
+  if (home && home !== null && home !== undefined) {
+    LOG_FILE = join(home, "mcpcat.log");
+  }
+} catch {
+  // If homedir() or join() fails, LOG_FILE remains null
+  LOG_FILE = null;
+}
 
 export function writeToLog(message: string): void {
+  // Skip logging if we don't have a valid log file path
+  if (!LOG_FILE) {
+    return;
+  }
+
   const timestamp = new Date().toISOString();
   const logEntry = `[${timestamp}] ${message}\n`;