[Misc] Refactor: Improve argument handling for conda command (#20481)

Signed-off-by: reidliu41 <reid201711@gmail.com>

vllm/collect_env.py

@@ -96,6 +96,7 @@ DEFAULT_PIP_PATTERNS = {
 def run(command):
     """Return (return-code, stdout, stderr)."""
     shell = True if type(command) is str else False
+    try:
         p = subprocess.Popen(command,
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE,
@@ -116,6 +117,10 @@ def run(command):
         err = raw_err.decode(enc)
         return rc, output, err.strip()
 
+    except FileNotFoundError:
+        cmd_str = command if isinstance(command, str) else command[0]
+        return 127, '', f"Command not found: {cmd_str}"
+
 
 def run_and_read_all(run_lambda, command):
     """Run command using run_lambda; reads and returns entire output if rc is 0."""
@@ -148,7 +153,7 @@ def get_conda_packages(run_lambda, patterns=None):
     if patterns is None:
         patterns = DEFAULT_CONDA_PATTERNS
     conda = os.environ.get('CONDA_EXE', 'conda')
-    out = run_and_read_all(run_lambda, "{} list".format(conda))
+    out = run_and_read_all(run_lambda, [conda, 'list'])
     if out is None:
         return out